Mutagen vs Carcinogen Mutagen and carcinogen are two terms that have a lot in common. There is a potential that a single substance could be both of them at the same time and be only one of the two, as well.
A curb bit is a type of bit used for riding horses that uses lever action. It includes the pelham bit and the Weymouth curb along with the traditional curb bit used mainly by Western riders. Kimblewicks or Kimberwickes are modified curb bits, and a curb bit is used in a double bridle along with a bradoon.
Roundover bits are normally used to create a smooth, even curve on a workpiece, but they also have one sharp cutting edge at the bottom of the radius that creates a 90-degree cut at the top of the roundover if the bit is fully extended. Used in this manner, a roundover bit makes a decorative thumbnail edge.