As with most other double locking tremolos, it is based on a design pioneered by Floyd Rose. It has two knife edges which rest against posts. The strings lock into the saddles, which can be adjusted for intonation. The tension of the strings is counter-balanced by a set of springs in the rear cavity which attach to a claw which allows the tension to be adjusted. Using this design, the bridge itself floats. Since the bridge mounted in a cavity which is routed out of the top of the guitar, the design allows the player to pull up or push down on the vibrato bar to adjust the pitch up or down — with a non-floating design the bar (and pitch) can only be pushed down.
Like the Edge Pro II and Lo-TRS II tremolos before it, the Edge III is made for mid-level and budget guitars, particularly those made outside of Japan. Although the name would imply that it was an evolution of the Edge and Edge II it is made with cheaper materials and processes than those tremolos which were used on high-end guitars.
The Edge III was partially phased out for mid-level instruments in 2011 with the introduction of the Edge Zero II with ZPS3 tuning stabilizer on many models. It continued to be used on budget guitars and in the US market where there was a patent dispute involving the ZPS design, until it was eventually replaced by the Standard DL tremolo.