FireFly FRED T-3 Short ExtensionFlashing Rear End Device N Scale End of Train device by Daniel Meyer Engineering. U.S. Patent Number 8,869,708 Truck Mounted, T rack Powered and T otally Self Contained DC and DCC Compatible This item is a Short Extension unit, contact us for Medium or Long Extension units at same price. All FireFly's are built on MT 100 ton Barber or Roller Bearing trucks, with 36" wheels. Other sizes by special request. Important Change regarding Wheelsets: Stock wheelsets are now the new Fox Valley wide tread wheels. Upgrade to BLMA or Fox Valley fine tread, no charge. When ordering please specify length and wheelset type desired. Please note, this listing is for a Short FireFly, with standard wheels. If there are no requests for length or wheelset, a Short FireFly with standard wheels will be sent. We charge the shipping fee per order, not per unit. Order more than one to save shipping costs. One Year Replacement warranty We can do custom requests, subject to $5.00 service charge, added to shipping, request invoice before paying! Return policy as listed above. All returns must be authorized before sending back. For Video of the FireFly in action, see us on FB!