Used for attaching the tube of a Berd-Air system to your printer. I have mine attached to the cooling shroud of my E3D. What's Berd-Air? It's a system that's been developed to provide part cooling without using fans on the hotend, but instead uses pumps and tubing. In addition to the weight savings, the air ends up right where it needs to be in ring around the tip of the hotend, cooling the part without extra cooling on the hotend itself. You can pre-order a kit here: http://www.themakerhive.com/shop/viewitem.php?productid=28

Print it, stick it, clip it, enjoy!

Attribution - Creative Commons

BerdAir, Clip, MakerHive