The Blue Sweet Iron Curb Gag from Bombers Bits has a sliding rope action on the cheekpieces, which applies pressure to the horse's curb groove via a leather pad, rather than the strong poll pressure applied with a conventional gag bit. There is still some mild poll pressure, as the top ring acts in a similar way to a hanging cheek snaffle.
Meanwhile the blue sweet iron mouthpiece with a single joint is designed to produce salivation and help the horse to accept the bit and comfortably relax his jaw. The mouthpiece is curved, which distributes pressure more evenly over the tongue and bars. The offset centre link reduces the nutcracker action and pressure points on the tongue.
It is designed to be used with two reins, so the curb pressure only comes into play when it is really needed.
Please note that the blue will fade with use.
Please note that the curb gag is only legal for the jumping phases of eventing under FEI rules if two reins are used (with one attached to the main ring of the bit). Bombers recommend that two reins are used with this bit in all circumstances.