A brilliant bit of kit, in my opinion, saves hours of mane and tail pulling and much less stressful/painful for the horse. I use the fine one for the tail and the broader one for the mane.
I used one on my horses mane it looked ok untill I tried to plait it what a mess as it breaks the hair at all difo lengths so bits stuck out everywhere and looked terrible also because it shreds it some quite short they ended up standing up spiky through the mane when it started growing as for the tail one it seems to do nothing pulls out a few hairs then that's it just combs it almost was pretty annoyed as forked out for a expensive oyster one and it totally never worked at all.