What is so special about Derwent Rexel Blackedge pencils?
The answer is that you often see short ones. Pencils only get short by being sharpened and if the lead inside them shatters then most carpenters, joiners, builders etc haven't got time to faff about sharpening them.
Blackedge pencils are not indestructible or warranted, they will break if you sit on them and there are cheaper pencils available, but next time you see someone with a short one - have a look and see what sort it is.
Oblong carpenters pencils are supposed to be sharpened with a knife to a chisel shaped tip so that they don't follow the grain, please don't buy a special sharpener for making them pointed.
The set includes three pencils, one of each hardness/grade: