I bought some collets online. One of the collets is marked 50 with an overlapping SA etched on the face. It is tough to get a 5mm piece of stock in the collet. The 50 on the collet does not look like it is a factory mark. Does the SA have any significance? Could this have been made or modified by an individual? Appreciate any comments.
The other collet is marked 18 but is way bigger; maybe high 40s or 50. It has an indentation or shelf around the opening. What kind of collet is this? What does the 18 mean since it is so much larger than a normal 18?