It doesn't. The Klein shell is 35mm in diameter, and BB30 is 42mm.

Robbie's shop either threaded the shell for Italian thread (36mm x 24tpi) and added 1mm spacers under each cup, or they bored the Klein bb shell out a few mm wider and pressed in an English sleeve. The first would be easier, and Shimano still makes Italian Hollowtech BBs. Install with loctite since the inner diameter will be .1mm undersized.

Italian threads are also convenient because you can just turn them all the way through the shell.


Edit: Early Klein road bikes used 68mm shells, later 94-96 BB shells were 72mm. If it is the later version it would have to be faced down 1mm per side rather than require spacers.