This great quality BGS Compression Tester is suitable for motorcycle and cars with 14mm or 18mm spark plugs. 300 mm flexible hose large (ø 70 mm) easy to read scale scale: 0 – 21 bar / 21,5 kg/cm² / 300 P.S.I. accuracy: /- 3% blow off valve to test engine valve and piston rings Shut down power of ignition coil before working with this tool!