A.S.F.(R) Ride Control(R) 50-Ton Fully Sprung Metal Trucks Code 110 (.110") 33" Smooth-Back RP-25 Wheels 1 Pair by Kadee Quality products / HO Scale Metal fully sprung equalized trucks. Mounts with a #2 or 2-56 screw, sold separately. The A.S.F.(R) A-3 Ride Control(R) 50-ton freight truck was introduced in the 1940s and is one of the forerunners of modern freight trucks. Features embodied into this design include a longer spring travel, no spring planks and constant friction control using friction castings in the bolster to dampen excessive lateral roll of the car. These design features allowed for a higher train speed with less danger of derailment than previous designs. ASF sold over 140,000 sets by 1949. This truck is excellent for modeling the transition era up to 1994 when friction bearings were no longer allowed in interchange service. Truck Features: *Code 110 (.110) 33h smooth back wheels *Accurate markings *Incredible detail true to prototype *Non-magnetic metal wheels *Highly flexible sprung trucks *Metal side frames and fully sprung bolster *Smooth tracking free rolling contoured insulated axles *RP-25 Free rolling wheels