Check the listing for details. HO Electrical Pick Up Wheels 36" Smooth Back:2 Wheel Sets with 2 Copper collars. Condition: New. Listed at 6.00 USD. A Simple System for Track Electrical pickup. for Model trainsMost forms of electrical pickup into locomotives, tenders or rolling stock used on model railways has been accomplished using "wipers". The problem with this metal wiper systems is that they depend on pressure applied to the wheel which does initiate a slowing of the rotation of the wheels due to frictional forces.A simpler approach is to rely on gravity and extract the electricity from the axle rather than the wheel. Instead of a wiper a fine tube of conducting metal such as a copper collar can be used to surround the metal axle to draw current. Of course this requires a wheel set that is insulated on one side either by a plastic wheel or metal wheel with plastic insert while the other metal wheel is directly attached to the metal axle. These two wheel sets are arranged on the truck with the insulated wheels set up opposite one another so each will pick up from one side of the track to provide electric current for lighting a passenger carriage. Two wire leads are soldered, one onto each collar. The wires are inserted through an access hole drilled into the floor of the passenger car and connected to a lighting circuit. (also available on Ebay)Each Kit consists of 4 x 36" wheels, 2 axles and 2 copper collars ( 3/8" L x 5/32" OD) , wiring and heat shrink tube plus instructions for installation. (see kit photo) Connection wires and heat shrink tubing are included for making in-cabin connections to the electric load such as lights, sound, motion etc.This Kit contains 36" wheel size (HO Scale 13/32" or 1 cm diam) with smooth back. See photos for more details or Project 4 at modeltrainsounds.com(33" wheel sets are also available on eBay, listed separately) Note: The truck is not included and soldering of connecting wires is required. (see website) The wheels are new and manufactured to NMRA standards by a leading USA manufacturer. BUY IT NOW $6 with fixed fee shipping of $4.5 on one or more kits.