One of our newest creations is the Nunn Finer® Gag Hanger. It converts any bit into a gag bit, by simply sliding the Gag Hanger underneath the headstall just like a Bradoon Hanger and attach the other gag cheek. Once attached, simply pull the rope/ring through the cheekpiece on any d-ring, full cheek, etc and attach the rein to the ring. It can be used with just a single rein, or with one attached normally to the bit cheek and another attached to the gag ring.
A great training tool for teaching strong horses how to come back without having to 'bit up'