Fastback bits by Greg Dutton. 2-3/8" h x 1-1/4" w port. The narrow stock of the port combined with the chain links on each side allows for palate pressure with limited tongue relief, yet even, gradual pull on the bars with a quick release overall. The more narrow base of the port, results in a rigid feel. This provides flexion, lift and more collection value than most chain bits. Non-pinch chain attachment on cheek. Moderate to severe rating. 8" Cheek.