I always used Liverpools for my Shetlands, but have been converted by Wally's french link butterfly pelhams. But as above, any bit is ok if the pony is happy and controllable in it.
For Sale - 2 17" GP saddles, w&mw, barefoot Cheyenne treeless (size 1), waterproof exercise sheet (L), 5ft3" blue/green tartan summer sheet (BNIB). 2 sets travel boots 1 new, Horseware, Full & 1 used, Pony/cob. Bits 4.5"-5.5" incl Liverpools.