The R-1A utilizes an external locking design. This design allows the manufacturing process to be more automated, thus reducing the cost. A benefit of the external locking mechanism is its added ruggedness. FireStik recommends its use in situations that involve continuous exposure to shaking and vibration. The R-1A may be used with antennas up to 4' (1.2m). Physically, the R-1A's installed dimensions are 2.5" (65mm) high by 0.600" (15mm) diameter. The upper and lower body parts are made of chrome plated machine brass. The locking pin is stainless steel and the spring is heat treated spring steel.