These Low Profile Fixed Barrel Adapters are light and fast! Machined of 6061 Aluminum to be lighter and thinner than the original FBA, these bad boys come in at only .4 oz!. The Low Profile is only .65″ overall, adding a mere .1″ to the length of the silencer when in use. The Lo Profile FBAs are rated for pistol level energy cartridges only. (i.e. Sub-Sonic 300 Blackout, 300 Whisper, 357 Magnum, etc.) These devices are backwards compatible with all Mystic and Infiniti silencers.