N Scale Package includes one front and one rear coupler. This conversion fits: Atlas: RS11 Locomotive. This kit includes completely assembled body mount couplers and pilots for front and rear conversions. NOTE: This kit includes a pair of #1027 couplers for curved track of 12” radius or more, plus a pair of #1025 couplers for use on layouts with radii of less than 12”. Use the coupler that best fits your needs. The #1027 coupler is assembled. If using the #1025 couplers, install them in the #1027 draft gear box.