There are 3 board sizes depending on the bracket used. 3-pot Stooge brackets are used with board ~ 3.8 x 4.2in The smaller BR-15 bracket boards (like MOTM-800 or MOTM-310) boards are ~ 2.2 x 5.5in The 'standard' MOTM boards using BR-1 brackets are ~ 4.3 x 5.5in Paul S.