@mantisfan101 Mine are 4+ inches now. I got them from @Elytra and Antenna about 18 months ago when they were maybe 1.5-ish inches. They arrived healthy and active and had a beautiful color from the start, and have been easy to raise in standard millipede conditions on the humid side. They stayed out of sight for long periods while they were growing, but now that they're adults (or close to it) they're out and surface active nearly every night. Here's a pic of one from a year ago after the first molt:
BTW, these are Orin's Apeuthes sp., which I think some people call Tonkinbolus, maybe because of confusion between overlapping common names?