Calibrators quickly field-check accuracy of pressure-type concrete air meters. With a calibrator in the water-filled base, air meter gauge should read 5% air. Two calibrators are used in a 0.25ft? meter for a 10% air reading.

HM-27 Lightweight Aluminum Calibrator is accurately machined to exact dimensions. They are sturdier than plastic, less expensive than brass models. 5.63x3.25in (143x83mm), HxDia.