The #118 Kadee Magne-Matic Coupler features a Metal Coupler (#5 Sized Head) and Whisker Spring. The #118 Coupler may be mounted with the  #232 draft gear box (not supplied w/Bulk Packs) or with manufactures cast-on coupler pockets. Manual uncoupling requires the #241 Dual Tool. The "SF" Shelf Coupler can be easily modified to look like the type "F" Shelf Coupler or "H" Passenger Car Coupler. It is not recommended to use a metal coupler directly on a metal surface or in a metal draft gear box to avoid the possible electrical crossover or shorting that may cause damage.