BNIB OO / N Gauge PECO PT-61 Flexi Loco Lift Kit (Double Unit). PT-61 Flexi Loco Lift Kit (Double Unit). The modeller simply selects the gauge that they want by sliding the two halves together until the right gauge has been selected (there are guide marks on the mouldings to help with that) and then self-tapping screws secure things in place.
The PECO PT-61 Flexi Loco Lift Kit (Double Unit) OO N would be most suitable in model railroading setups where locos need to be easily removed and transported from tracks.