[en] The Wallace RD-8 is a portable, battery-operated survey meter covering an exposure rate range from 0.01 mR/h to 300 R/h. The instrument was designed specifically for military and civil defence applications and is accordingly of particularly rugged construction and claimed to be both waterproof and shockproof. This instrument is unusual in that it has two internally mounted radiation detectors. An end-window GM tube is used to cover the range from 0.01 to 300 mR/h, and a GM tube covers the range from 0.01 to 300 R/h. Both tubes have energy compensation sheaths for the measurement of photon radiation in the forward direction. Only the first tube permits the measurement of β-radiation. The information is given under the following headings; Facilities and controls; radiation characteristics; electrical characteristics; environmental characteristics; mechanical characteristics; summary of performance; calibration procedure; conclusions. (U.K.)