Changing out the edger blade is simply a matter of removing a nut and two washers, removing the old blade, and then installing the new blade, the two washers and the nut. However, my 2-pack of blades came with two slightly different quick guides on how to do the change out. Both guides stated what I described above, but one of the guides also stated that the nut had to be removed clockwise and re-installed and tightened counter clockwise. In other words the shaft and nut are reverse threaded. If someone doesn't know this and followed the incorrect guide that was in the pack they would simply be tightening the nut by trying to turn it in the normal counter clockwise direction. The second incorrect card should never have been included in the 2-pack, but I bought two sets of 2-pack replacement blades and both packs had two quick guides, one correct guide and one incorrect guide.