This is an RC4WD 12mm Mini Hex +15mm Wheel Widener Set. Works on any 12mm back Hex Wheels, such as those on Tamiya F-350, Tundra, Jeep, Axial AX10, Losi Crawler, RC4WD Timberwolf, Bully.
OD: 0.51 in / 13 mm
Width: 0.04 in / 1.1 mm
Internal Diameter: 0.24 in / 6.2 mm
4x Mini 12mm Widener
4x Barrel Nuts
8x 1mm Spacer with M6 Hole (Silver)
8x 1.2mm Spacer with M6 Hole (Silver)