Half-Round (Bullnose) Router Bits - 1/2 Shank, Carbide Tipped - Southeast Tool SE1436; 1 1/2 Cutting diameter, 1 7/8 Cutting length, 3 3/8 Overall length.
Braze tools ( CT carbide tipped or TCT Tungsten Carbide Tipped ) Have a piece of expensive tungsten carbide brazed to a steel shaft. This gives you the incredible long wear of carbide (up to 100 times that of steel) and the toughness of a steel saw plate, router shaft, etc. It makes a clearly superior tool at a greatly reduced cost.
Brazing is the joining of two dissimilar materials through the use of a third material at temperatures above 800° F. (There are other definitions but they are all pretty close to this.)
Carbide brazing is done with a high silver braze alloy. The braze alloy (silver solder, high silver solder, high temp silver solder) is about 50% Silver. This makes it expensive but it is really worth it. Unlike other attachment methods, good brazing forms a mechanical and a chemical bond between the carbide and the steel so that the bond is much stronger than either the steel or the carbide. It also acts like a suspension on a car in that it cushions the hard carbide tool tip to protect it from chipping, breaking and excess wear.