"I bought these shears to cut PE-X pipe (15mm and 22mm). They were sharp and cut quickly, but none of the cuts were square to the pipe. They consistently cut at a slight angle, which I then had to true up with a knife.
I may have had a faulty pair, but the problem appeared to be that the plastic from which the shears were made was not rigid enough to hold the blade absolutely straight while cutting. Consequently, the blade kept wandering out of true as it went through the pipe. In the end, I returned the shears to Screwfix and used a utility knife instead."