The sizes listed on the catalog section are based on common forklift fork sizes, 4" (100mm) fork have an internal width of 4.04" (102mm), likewise, 5" (125mm) is 5.02" (127.5mm) inside, 6" (150mm) are 6.00" (152mm). Correspondingly the external withs are 4.82", 5.57", and 6.91". The cushion thickness is .531" on each width and the sidewall height is .945"