Sweet iron will rust when it comes into contact with (air) humidity; the surface rust tastes sweet and naturally stimulates the saliva production. This will cause the horse to salivate more which in turn encourages better acceptance of the bit. The rusting process (oxidation) changes the blue colour of the TRUST-bit to a brownish-grey.
If a sweet iron bit is not used for a while, an orange-brown rust layer may develop on the mouthpiece. Simply remove this by wiping the bit with a damp cloth.
An eggbutt is a basic bit, in general a soft bit. The bit rings are oval and fixed to the mouthpiece, which gives a more direct reaction from the aid. The rubber bit guards are not needed. The bit is relatively stable in the horses mouth.
The eggbutt snaffle bit is very suitable for young horses and riders with a average hand.