Shires Elastic Training Reins in Black. The Shires Elastic Training Reins can help encourage the horse to work in the correct outline and are made from 6mm tubular elastic with an adjustment section at the poll. To fit the training aid the reins are passed down from the poll, (with the adjustment section remaining at the poll) to the bit, where it is then either clipped backwards onto the girth or on to the D rings of the saddle, the poll section can then be adjusted accordingly.