Make sure your knife says "Modern Roofer®" for safety and beware of knock-offs.
Whenever you see a knife for sale that looks like the Modern Roofer®, but without a blade in the end, look out because it is an unsafe counterfeit knife! These knives are even distributed by one company and private labeled for others.
Similarly, the handles of the painted, (often yellow), knockoffs also do not fit together, allowing blades stored in the handle to slip out or the end blade to rotate and cut the user. Both of these types of knockoff knives are poorly made, over priced, and dangerous to use.