Designed for motorcycle use. Includes a metal clip that can be clipped to the gauge. The gauge can then be clipped to the bike's frame or handlebar leaving pour hands free. Includes adapters for 10mm, 12mm, 14mm and 18mm threaded spark plug holes. The gauge is 2-1/2" (6.4cm) diameter and has a dual scale dial that shows 0-300 psi and 0-21 bar.