The RC-292 is a VHF Low Band 1/4 wave vertical antenna with ground plane. RC stands for Radio Component and this antenna was the successor to the RC-291.
The vertical and ground plane elements are made up of AB-21 series elements in the stock configuration or could also use MS-116 series screw together antenna elements. The antenna only covers a small percentage bandwidth so different numbers of elements are needed to match a given frequency in the 30 to 88 MHz range used by Squad Radios. Because of this bandwidth limitation the RC-292 can not be used with frequency hopping radios, like the SINCGARS, and so the OE-254 was developed.
This antenna is very reliable and has low loss when the correct number of elements are used for the desired frequency of operation. Getting the RC-292 on top of a 30 foot mast adds a great deal of range when compared to a vehicle mounted antenna, like the AS-1729.
The OE-254 uses the MS-116 series antenna elements which have the same mating threads as the AB-21 series elements used on the stock RC-292. These have copper as the exposed metal and when joined the copper oxidizes locking the elements together. The male threads should be polished and a light coat of Radio Shack Lube Gel applied prior to assembly.
The RC-292 came out about the time of the PRC-8, PRC-9 and PRC-10 radios. The three different element configurations of the RC-292 match the coverage of the three radios.
Although mostly used for VHF low band it can be used as an HF antenna by using as many vertical antenna elements are you're comfortable with and adding wires to act as the counterpoise.