Fastrax 1:8 15mm Extension Hub Adaptors - to Widen Track (17mm Hex) FAST920. This product is designed to widen the track of your 1:8 scale RC vehicles. It features 15mm extensions and 17mm hex adaptors for a secure fit. Keywords: Scalextric, Hornby, Models, Radio Control, Sylvanian Families, LEGO, Tamiya, Plastic Model Kits, Playmobil, Italeri.