Nema 17 just like the MPCNC/LR2, for linear rails I had all of then left from another project but I ordered from Amazon (400mm), @barry99705 post somewere about an upgrade rail today… and I can’t find it where he post it.
Edited… (found the link) https://forum.v1e.com/t/new-printer-time/28127/633?u=gpagnozzi
If you can’t find the 275mm, get a longer one, you can always use a cutting wheel to make it to size.