New Adapter Reaches Difficult Access Points Equus Products now offers its 8" long reach adapter, the INNOVA 3619 Compression Tester Extension. This adapter safely and easily accesses recessed spark plug holed to perform compression tests on vehicles with difficult access points, including SOHC (single overhead camshaft) and DOHC (dual overhead camshaft) applications. The 3619 can be used with any Equus compression testers including the 3214 Pro Compression Tester, 3612 Compression Tester 4-pc. Kit and the 3614 Compression tester 6-pc. Kit.