REPLACEMENT POP-IN MOBILE BOARD CASTERS FOR GLOBAL INDUSTRIAL MOBILE BOARDS 4/SET REPLACEMENT CASTERS FOR THE GLOBAL INDUSTRIAL MOBILE WHITEBOARDS (B444997 B444999 B1854285 B444997A B444999A B1854285A). 3"" DIAMETER WHEELS. COMES IN A SET OF 4 CASTERS. TWO LOCKING CASTERS TWO NON-LOCKING CASTERS.