Review on 40Pcs Parallel Hardened Precision Machinist: Ensuring Accurate and Consistent Machining Results by Daniel Ogbebor

This is the bare minimum you need for thin parallels. Other than that, they match the bar I have. They're pretty parallel, which is good news. However, they're wrapped in gooey cosmoline instead of oil, making cleaning each pair a chore. And they have black oxide on the sides (top/bottom beveled/cut/honed only) that needs to be soaked in oil to prevent rust, so I don't really understand why. Or maybe the black sides are mill scale, and why black oxide? The box is the cheapest blow molded plastic box you can imagine. They feel like someone got some quality scissors and adjusted them to get parallel cuts from sheet stock rather than grinding tool steel to size, but I don't know exactly how they're made and they're a bit smaller (by a few tenths) and fairly parallel (the two pairs I've used so far have about a tenth the difference between sides).