Threaded Leg Collars are perfect for attaching your phones, tablets and other accessories to your tripod. Designed for versatility, these collars feature two 1/4"-20 sockets spaced 30mm apart so you can attach a B2-LR II to your tripod leg. Or use the countersunk center 3/8"-16 hole for attaching other accessories. The anti-twist slot allows you to mount a ball head to the tripod leg for additional freedom in positioning accessories.