Susan Bates Twist Lock Intchg Crochet Hook Component Set Sizes H8/5mm and I9/5.5mm. The Twist Lock Interchangeable Crochet Hook offers a convenient way to carry or store two different sized hooks in the oversized soft-touch handle. Crochet hook heads feature the popular in-line construction for uniform stitching and reduced wrist strain. This package contains hook sizes H and I, plus a cutter. Handle not included.