For the Price These are a great set of sturdy castors. These are now fitted to my 2x12 cab, 2x12 Combo and 1x12 cab (OK, a bit lazy I know) and a very heavy active wedge Monitor.
The two locking castors look OK, but the locks are only made of plastic, so I don't know how long they would last with continuous usage. The castors themselves are wel made with a proper nut and bolt through the wheel and not just a pop-rivet as can been seen on some castors.
Quality of the screws is OK, buth then again you can easily swap these for some heavy duty screws.
As I say, for the price you cannot really go wrong.
Highly recommended