The Blue sweet iron polo double mouth gag with guards is a stronger bit due to the centre links of the two pieces being offset by 20mm giving it a double nutcracker action, which creates more tongue and bar pressure.
That riders may use on the older stronger horses.

The Gag comes with bit guards to minimise pinching and is suitable to use with one or two reins on the ring and the running gag ropes.
The gag ropes going through the rings create leverage which will exert more pressure through the mouthpiece whilst at the same time introducing more poll pressure.

The big ring creates more leverage making it stronger than the small ring version and more direct action when turning.
The blue sweet iron oxidises easily, encourages salivation and helps with bit acceptance

Cob - 12.5cm Full - 13.5cm