These are blades from various suppliers in the UK and the EU.  Commonly referred to the floor fitters as hooks and straights.   Refers to blades that fit trimming knives such as the Dolphin, Janser and Stanley.  It also has blades that fit trimming tools such as the araseur floor trimmer and the Hi-Tech Trimmer.  The blades will also fit the various carpet cutters on the site such as the crain 245 deluxe and the crain 246 econo carpet trimmer.  The Hooked carpet blades is a reversible large twin-hook blade, ideal for cutting carpet. The hook shaped blade is ideal for slicing accurately through individual layers of carpet, without inadvertently damaging layers beneath the cutting surface.  This will be the most important (and possibly the only) tool you’ll need to cut carpet. A standard utility knife is preferable, though something like an Dolphin knife can also do the trick. Whatever you use, make sure the edge is nice and sharp.