... 2" to 8", lever, bolt and wedge type for all concrete pumping systems. Concrete pump clamps Size2", 3", 4", 5", 6", 8 ... "MaterialHi-Mn 13, 20# steel Typesnap clamp, bolt clamp, screw clamp, wedge clampTechnicalprecise castingApplicationconnection ... couplings;3, No grooved couplings when pumping concrete. Boom Pipe Wedge Coupling