Most Track bikes are still made with Threaded Bottom Brackets for stability and strength. The ISIS cartridges thread in and can be fitted to most frames and have some adjustability to fit differing chain lines and carbon tolerance imperfections. The normal threaded BB is 68mm in diameter and the standard width of the ISIS BB for a track bike is 108mm.
These are readily available anywhere in the world and many track bikes already have them installed. Hence, Verve does not supply the BB, allowing you to choose the quality that you prefer. The downside with ISIS (or Square taper) Cartridge BB's is that the bearings are quite small and they "wear out" quite quickly. However, they are also not very expensive generally.
Some people ask about Ceramic ISIS cartridges. The only ones that we are aware of come from a US company called Omni. We have not tested them, but they make big claims about them. We have attached some screenshots of a couple of well-known versions.