We have had to replace ours every year or 2 due to the chains getting jammed and splitting the casing open. Every time we have bought a black whitco assembly, with the half distance open limiter installed so it cant be fully wound out, and they continue to do this. No faults with the gears or the handle, just the chain forcing the casing to split open. Sick of it.

Because you could not supply the quantity I needed I finished up getting them in different orders and now I have 4 different keys. Not the end of the world but just a nuisance.

This window winder was easy to install and has an excellent winder, and works well with the window frame and screen.