Abstract: A modular shelving system has a plurality of spaced apart vertical members with parallel side surfaces and a plurality of aligned holes defined in the side surfaces. A plurality of tray members are removably installed to the support rails by detent pins which engage the holes in the support rails. Automatic locking by deflectable portions of the tray bottoms locks the tray members to the support rails. Each tray member has a pair of detent pins carried on opposing side walls of the tray member. The detent pins are substantially perpendicular to the bottom of the tray, thus causing the tray to be cantilevered substantially horizontally from the support rails when the detent pins engage the holes in the support rails.