To change the blade, simply unscrew the four security screws/bolts, separate the two handle scales, and replace the blade. Please note that the three screws closest to the blade will only unscrew from the front of the handle (with the Casström logo facing you) as the bolts inserted from the back are fixed in their position. The fourth screw and bolt at the end of the handle may require two Allen keys/hex tools to be undone.