This is a Peco OOT48 HO Tracksetta Track Laying Template -- 48 121.9cm Radius Curve. Coated steel template makes it easy to lay track with smooth curves and straight lines without dog-legs. Simply fit between the rails to hold the track in_position and pin track down through the slots. With Tracksetta, reverse and transition curves can be laid easily and accurately even when working alone. An invaluable aid.