Mine is a squeeze open type, that pops around the post, then it has two nuts and bolts to clamp it down. With a 28.6
OD seat tube, the clamp jaws go flat, just as it tightens down on the tubing. $29.99 is not cheap. 8 dollars for Master
lock and 3-4 bucks for a 2 foot length of chain is cheap.,,,,BD