Product details:

OEMTools 27138: Compression Tester, 0-300 psi, 2 1/2 in. Diameter Gauge, Black Rubber Hose, 18 in. Hose Length, Kit - OEM Automotive Tools compression testers test engine compression from 0-300 psi on 14mm and 18mm spark plug ports. The testers include a flexible rubber hose extension and come packed inside a sturdy molded plastic storage case. Order the kit with adapters and components needed for your diagnostics.Test Compression 0-300 psi on 14 mm and 18 mm Spark Plug Ports.
Flexible Rubber Hose Extension.
2 Step Adapter 14 and 18 mm.
SAE Sizes: 1/4, 5/16, 3/8 and 7/16 In.