Bombers 4 Ring Barry Reversible RTThe 4 Ring has 2 rings on the bottom to adjust the amount of poll pressure and leverage you want. The Barrie Reversible is a severe bit due to the center links of the two pieces being offset by 20mm giving it a double nutcracker action, which creates more tongue and bar pressure. All our bits are made from blue sweet iron, because it: oxidizes easily encourages salivation helps bit acceptance is warm and sweet Please note the blue will fade with use.