Kit includes pressure tester connector with 3 adapters to fit almost All cooling systems. 3 adapters cover All diameters from 17mm to 40mm. Elastomeric adapters with wide durometer ratings. All adapters with O-rings. Connector works with All standard pressure tester pumps. Connector manufactured from aluminum, steel & durable plastic. California prop 65 - warning, this product contains chemicals known to the state of California to cause cancer, birth defects or other reproductive harm.