Weaver Brand Biothane Miniature Harness. Complete Set Including the Pad & Bit.
Bridle Measures 35" at the largest and 25" at the smallest tip to tip over the poll. (remember your bit will add some length due to the rings) The saddle measures 48" at the largest and 38" at the smallest around the inside.
The easiest way to know is If this will fit is using a bale string, measure corner of the mouth to other corner over the poll and then right behind the withers, Then measure the string and compare the measurements above.