I am not often moved to write about or review guitar or mandolin accessories. But this thing is so bad, so useless, I must say something.
Just don’t waste your money. Note the slot through which the strings must pass. It is too narrow. The outer string have no where to go. The genius who designed this thing never saw or touched a mandolin. Also, the hooks do not work.
Brand names selling this: Golden Gate (Saga), Magideal, Milisten, Alnicove, Bstinay.