The AEP 2153 is a multi-purpose survey meter used for measuring gamma radiation fields. The meter measures 20 cm in length and is 23 cm tall. The probe assembly is 17 cm long and has a 3 cm diameter active area. The detector has two halogen-quenched Geiger tubes – one for the 0-100 mR/h range, the other for the 0-10 R/h range. Low-range is the default, and the high range is activated by the user pulling the trigger on the handle. A movable shield covers the low-range Geiger tube and when swung out of the way allows the entry of beta radiation. This instrument was used at Chalk River.