3/4"
https://www.youtube.com/watch?v=VdESb8_p5ec
Enjoy them! The quilt studio where I rent time has one machine with Leadergrips, and one where you have to pin to the leaders. I find it takes me about 30 min less to load a queen-sized quilt when using the Leadergrips than pinning, and much less chance of poking myself and bleeding on the quilt - a worthwhile investment!