Otter Aluminium Open Blind Rivets are a two-part fastener consisting of a shell and a headed stem mandrel assembled so the shell can be placed into the work to be fastened. The rivet is set by drawing the stem through the shell, which causes the body to expand/compress to distort and clamp the material securely. After the desired clamping force is achieved, the stem breaks off at a predetermined position and is discarded. A small portion of the stem remains trapped in the bottom of the shell to ensure the clamping force is retained in the joint. Blind rivets are designed to clamp together specific thicknesses of material. If the grip range is less than it should be (the rivet is too long), excessive material will be left on the blind side and more pulls will be required to break-off the mandrel. If the grip range is too large (rivet is too short), insufficient material may be left on the blind side to secure the joint. Aluminium blind rivets are the most popular fixing used for most sheet fabrications and general purpose applications with a plain aluminium finish. Used for windows, security doors, tool boxes, garden sheds, down pipes, guttering, air conditioning ducts and general purpose external.