Jefferies Harmony Four Ring Gag Jefferies Harmony Four Ring Gag £30.95 imperial size: [None]5"5.1/2"6" metric size: [None]12.513.514.5 Quantity: at £30.95 each Add To Basket NEW FOR 2019. The shaped mouthpiece (similar to the NS Verbindend) is now available in a Four Ring Gag. Ergonomically designed. 90% Copper Mouthpiece to help promote salivation. The moutpiece has a more defined angle which allows more precise aids, but still allows a light contact to promote a softer but quicker response. Better picture to follow.