The model 19 has an internally mounted 1" x 1" sodium iodide detector, sensitivity: typically 175 CPM/Micro R/HR, range selections, 0-25, 0-50, 0-250, 0-500, 0-5000, The cast aluminum instrument housing with its separate battery compartment and accompanying metal handle offer an industrial robustness and quality that promote long lasting protection and instrument life. The model 19 has a built in unimorph speaker with on/off switch, uses two "D" cell batteries, weight 4.5 lbs.