I dont know if you can buy something simular?A while ago i got a mate who welds to make me a couple of brackets to hook onto a cat ladder.It looks simular to a ladder stay.I use it for stacking slates/tiles on.Its alot safer/easier than just trying to put them between the rungs of the cat ladder and certanly alot easier than carrying them down then back up.Ideal for valleys/fitting dry verge etc.Has anyone got any other home made gadjets that could be useful in roofing they could share?I wont copy/patent them "honest" .