The 1 1/2" big nickel and antique brass finish bolt snap hooks come with u-shape sleeves. You can open or close the bolt snap hooks eaily by sliding up and down the u-shape slider by your finger. You can open or close the bolt snap hooks eaily by sliding up and down the u-shape slider by your finger. This item can be used as an attachment to dog leashes, marine devices,charms,lanyards and purse straps.