diff --git a/Svelto.ECS/EntityViewsDB.cs b/Svelto.ECS/EntityViewsDB.cs
index cca5551..e14f958 100644
--- a/Svelto.ECS/EntityViewsDB.cs
+++ b/Svelto.ECS/EntityViewsDB.cs
@@ -60,7 +60,7 @@ namespace Svelto.ECS.Internal
             return entityView;
         }
 
-        public bool EntityExists<T>(EGID entityGID) where T : IEntityData
+        public bool Exists<T>(EGID entityGID) where T : IEntityData
         {
             var type = typeof(T);
 
@@ -83,13 +83,23 @@ namespace Svelto.ECS.Internal
 
             return false;
         }
-        
-        public bool TryQueryEntityView<T>(EGID entityegid, out T entityView) where T : class, IEntityData
+
+        public void Fetch<T>(out T entity) where T : IEntityData
+        {
+            entity = QueryEntities<T>()[0];
+        }
+
+        public bool Has<T>() where T : IEntityData
+        {
+            return QueryEntities<T>().Count > 0;
+        }
+
+        public bool TryQueryEntityView<T>(EGID entityegid, out T entityView) where T : IEntityData
         {
             return TryQueryEntityViewInGroup(entityegid, out entityView);
         }
 
-        bool TryQueryEntityViewInGroup<T>(EGID entityGID, out T entityView) where T:class, IEntityData
+        bool TryQueryEntityViewInGroup<T>(EGID entityGID, out T entityView) where T:IEntityData
         {
             var type = typeof(T);
 
diff --git a/Svelto.ECS/IEntityViewsDB.cs b/Svelto.ECS/IEntityViewsDB.cs
index 0711e1e..2541bc6 100644
--- a/Svelto.ECS/IEntityViewsDB.cs
+++ b/Svelto.ECS/IEntityViewsDB.cs
@@ -13,9 +13,11 @@ namespace Svelto.ECS
         T[] QueryEntitiesCacheFriendly<T>(int group, out int count) where T : struct, IEntityData;
 
         //to use with EntityViews
-        bool TryQueryEntityView<T>(EGID ID, out T entityView) where T : class, IEntityData;
-        T    QueryEntityView<T>(EGID entityGID) where T : class, IEntityData;
+        bool TryQueryEntityView<T>(EGID egid, out T entityView) where T : IEntityData;
+        T    QueryEntityView<T>(EGID egid) where T : class, IEntityData;
         
-        bool EntityExists<T>(EGID ID) where T : IEntityData;
+        bool Exists<T>(EGID egid) where T : IEntityData;
+        void Fetch<T>(out T entity) where T:IEntityData;
+        bool Has<T>() where T:IEntityData;
     }
 }
\ No newline at end of file
diff --git a/Svelto.ECS/MultiEntitiesEngine.cs b/Svelto.ECS/MultiEntitiesEngine.cs
index 9805cfa..709bb8c 100644
--- a/Svelto.ECS/MultiEntitiesEngine.cs
+++ b/Svelto.ECS/MultiEntitiesEngine.cs
@@ -1,7 +1,7 @@
 namespace Svelto.ECS
 {
-    public abstract class MultiEntitiesEngine<T, U> : SingleEntitiesEngine<T>, IHandleEntityStructEngine<U>
-        where U : struct, IEntityData where T : struct, IEntityData
+    public abstract class MultiEntitiesEngine<T, U> : SingleEntityEngine<T>, IHandleEntityStructEngine<U>
+        where U : IEntityData where T : IEntityData
     {
         public void AddInternal(ref U entityView)
         { Add(ref entityView); }
@@ -13,7 +13,7 @@ namespace Svelto.ECS
     }
     
     public abstract class MultiEntitiesEngine<T, U, V> : MultiEntitiesEngine<T, U>, IHandleEntityStructEngine<V>
-        where V :  struct, IEntityData where U :  struct, IEntityData where T :  struct, IEntityData
+        where V :  IEntityData where U :  IEntityData where T :  IEntityData
     {
         public void AddInternal(ref V entityView)
         { Add(ref entityView); }
@@ -30,7 +30,7 @@ namespace Svelto.ECS
     ///     already too many responsabilities.
     /// </summary>
     public abstract class MultiEntitiesEngine<T, U, V, W> : MultiEntitiesEngine<T, U, V>, IHandleEntityStructEngine<W>
-        where W :  struct, IEntityData where V :  struct, IEntityData where U :  struct, IEntityData where T : struct, IEntityData
+        where W :  IEntityData where V :  IEntityData where U :  IEntityData where T : IEntityData
     {
         public void AddInternal(ref W entityView)
         { Add(ref entityView); }
diff --git a/Svelto.ECS/MultiEntityEngine.cs b/Svelto.ECS/MultiEntityEngine.cs
deleted file mode 100644
index 062568b..0000000
--- a/Svelto.ECS/MultiEntityEngine.cs
+++ /dev/null
@@ -1,43 +0,0 @@
-namespace Svelto.ECS
-{
-    public abstract class MultiEntityStructsEngine<T, U> : SingleEntityStructEngine<T>, IHandleEntityStructEngine<U>
-        where U : struct, IEntityData where T : struct, IEntityData
-    {
-        public void AddInternal(ref U entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref U entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref U    entityView);
-        protected abstract void Remove(ref U entityView);
-    }
-    
-    public abstract class MultiEntityStructsEngine<T, U, V> : MultiEntityViewsEngine<T, U>, IHandleEntityStructEngine<V>
-        where V :  struct, IEntityData where U :  struct, IEntityData where T :  struct, IEntityData
-    {
-        public void AddInternal(ref V entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref V entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref V    entityView);
-        protected abstract void Remove(ref V entityView);
-    }
-
-    /// <summary>
-    ///     Please do not add more MultiEntityViewsEngine
-    ///     if you use more than 4 nodes, your engine has
-    ///     already too many responsabilities.
-    /// </summary>
-    public abstract class MultiEntityStructsEngine<T, U, V, W> : MultiEntityViewsEngine<T, U, V>, IHandleEntityStructEngine<W>
-        where W :  struct, IEntityData where V :  struct, IEntityData where U :  struct, IEntityData where T : struct, IEntityData
-    {
-        public void AddInternal(ref W entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref W entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref W    entityView);
-        protected abstract void Remove(ref W entityView);
-    }
-}
\ No newline at end of file
diff --git a/Svelto.ECS/MultiEntityStructsEngine.cs b/Svelto.ECS/MultiEntityStructsEngine.cs
deleted file mode 100644
index 2e501d4..0000000
--- a/Svelto.ECS/MultiEntityStructsEngine.cs
+++ /dev/null
@@ -1,43 +0,0 @@
-namespace Svelto.ECS
-{
-    public abstract class MultiEntityStructsEngine<T, U> : SingleEntityViewEngine<T>, IHandleEntityStructEngine<U>
-        where U : IEntityData where T : IEntityData
-    {
-        public void AddInternal(ref U entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref U entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref U    entityView);
-        protected abstract void Remove(ref U entityView);
-    }
-    
-    public abstract class MultiEntityStructsEngine<T, U, V> : MultiEntityViewsEngine<T, U>, IHandleEntityStructEngine<V>
-        where V :  IEntityData where U :  IEntityData where T :  IEntityData
-    {
-        public void AddInternal(ref V entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref V entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref V    entityView);
-        protected abstract void Remove(ref V entityView);
-    }
-
-    /// <summary>
-    ///     Please do not add more MultiEntityViewsEngine
-    ///     if you use more than 4 nodes, your engine has
-    ///     already too many responsabilities.
-    /// </summary>
-    public abstract class MultiEntityStructsEngine<T, U, V, W> : MultiEntityViewsEngine<T, U, V>, IHandleEntityStructEngine<W>
-        where W :  IEntityData where V :  IEntityData where U :  IEntityData where T : IEntityData
-    {
-        public void AddInternal(ref W entityView)
-        { Add(ref entityView); }
-        public void RemoveInternal(ref W entityView)
-        { Remove(ref entityView); }
-        
-        protected abstract void Add(ref W    entityView);
-        protected abstract void Remove(ref W entityView);
-    }
-}
\ No newline at end of file
diff --git a/Svelto.ECS/SingleEntitiesEngine.cs b/Svelto.ECS/SingleEntityEngine.cs
similarity index 74%
rename from Svelto.ECS/SingleEntitiesEngine.cs
rename to Svelto.ECS/SingleEntityEngine.cs
index 5924f2c..dbf0757 100644
--- a/Svelto.ECS/SingleEntitiesEngine.cs
+++ b/Svelto.ECS/SingleEntityEngine.cs
@@ -1,6 +1,6 @@
 namespace Svelto.ECS
 {
-    public abstract class SingleEntitiesEngine<T> : IHandleEntityStructEngine<T> where T : struct, IEntityData
+    public abstract class SingleEntityEngine<T> : IHandleEntityStructEngine<T> where T : IEntityData
     {
         public void AddInternal(ref T entityView)
         { Add(ref entityView); }