This is the official name of this small tool. very simple but very clever.
You may know how awful to mark hemline evenly especially in case of full or half skirt.
This Pin it vintage skirt marker resolve this problem easily. put this tool on the floor and fix your desire lenghth and turn around your skirt or yourself( if you are wearing skirt and if somebody else helps you) and clamping, pinning, releasing. that’s all.
I found this vintage(50′-60′) pin it at trift store few years ago. paid only 5 swiss fran. that’s also why i love thrift shopping.