You may think of them as ascenders or rope grabs, but for arborists, these are mechanical adjusters. They are used to quickly and easily adjust the length of your flipline while climbing. They have a few advantages over prusik loops or simple knot tying. They are durable and difficult to cut or damage compared to rope. Additionally, you can use them with just one hand, leaving your other hand free. They fasten securely to your flipline using a bolt and nut as opposed to a locking pin, a style more common with climbing ascenders.
These "rope grabs" are also used as ascenders for rope climbing. If you're looking for more ascender options, then be sure to check out our Ascenders
on their own page. You can also find Rope & Cable Grabs
for use with Vertical Lifelines
in our separate Fall Protection