Size of what??? Harness is shetland size and recommended to me fits her fine just one extra hole for bit. Otherwise it is just resting on her as first time on her. We cannot go any smaller than shetland size. It will look odd as just out of the packaging so sits proud once molded round it will be fine.
Both the seller of the harness and Robinsons say I need shetland size,
livery helping me is qualified in training driving. Says harness is fine
size of pony ???
I brought her 2008 I knew how big she was to teach children on!!!
Had my first lesson long reining her with the harness on ( done it before when i broke her in) but harness long rein is different. I was told I did really well, and pony was a good girl as only 2nd time with it on inc blinkers.