A tie down strap (also known as a ratchet strap, a lashing strap) is a fastener used during transportation to hold down cargo or equipment. Tie down straps are simply webbing that is equipped with hardware to tie down. This hardware enables the tie down strap to be connected to the cargo or equipment surrounding area, to loop over the cargo or equipment,and/or to attach to the cargo or equipment. A tensioning tool for the harness, such as a ratchet, is typically often included.
A smaller handle that disconnects the ratcheting handle is the release catch, also referred to as the release lever. It's located in the center of the ratchet's top movable bit. Pull up the release catch and flip open the ratchet absolutely. Set the open ratchet before you on a table so that the spiked wheels (cogs) face upward.
The length of the strap is held by the slot at the bottom of the ratchet, known as the "mandrel." Start from underneath the ratchet and force it up through the mandrel to thread the harness. Then the threaded strap should lie straight, the length of it matching on the other side of the ratchet with the second strap.
Mind that you can still tighten it later with the ratchet, so don't think about the length too much.