American Limited Models N Scale Working Diaphragm kits make adding operating diaphragms to your passenger cars and locomotives fast and fun, and they fill the unsightly gap between passenger cars and cab unit diesels. Easy-to-build kits feature injection-molded plastic parts, in black or gray plastic. Diaphragms are sprung to hold together on curves. Will not interfere with operation of most couplers. All working diaphragm kits include complete instructions. Kits are designed to fit specified cars or cab unit locomotives. Check out the variety of American Limited N Scale passenger car and locomotive diaphragms. For A-B-A sets (four diaphragms). Kato F units require Micro-Trains (R) #1128 couplers E units use standard Kato couplers. 12′ minimum radius.