Draper - Digital Petrol Compression Test Kit (8 Piece) Expert Quality, compatible with direct and indirect petrol engines which use 10, 12, 14 and 18mm spark plug threads. Attached with a digital LCD display gauge with a choice of three pressure scales 0 - 300psi/0 - 20bar/0 - 2000kPa and fitted with a heavy - duty rubber protector. The braided stainless steel hose improves durability. Fitted with a spring - loaded pressure relief valve and integrated Schrader one - way valve system. Supplied in a plastic storage case.