OPTIONAL BIN RAIL KIT INCLUDES 9 RAILS THAT ALLOW USE OF AKROBINS (SOLD SEPARATELY IN CARTON QUANTITIES ONLY) FOR A MOBILE WORKSTATION. RAIL KIT HOLDS 1 CASE OF 12 PIECES 11""W X 10-7/8""D X 5""H BLUE OR YELLOW AKROBINS OR 1 CASE OF 12 PIECES 8-1/4""W X 10-3/4""D X 7""H BLUE OR YELLOW AKROBINS.