I bought a used Sinclair NT-4000 with all of the mandrels. On the 6MM set, there are three mandrels; one with the "E24" stamped expander mandrel and a plane one (no stamp) which is the turning mandrel but there is another one with a "T24" stamped. The plane mandrel reads .241", the E24 mandrel reads .242" and the T24 mandrel reads .240.5". I'm wondering what the "T" mandrel is for? I called Brownell's and they don't know....