The Gamegenic Sidekick Pro 100+ XL Convertible has a small tray
that slides out of the bottom of the box for dice, tokens and counters. Its
dimensions aren't published anywhere I could find, so I measured mine.
Dimensions are approximate (my calipers aren't the best):
Tray (outside): 85.7 × 80 × 33.7 mm
Tray (inside): 75.1 × 69.4 × 28.4 mm
Tray cubby: 88.5 × 80 × 36 mm
The cubby is 2.3 mm taller than the tray, and that headroom is usable, so the
usable space is about 75.1 × 69.4 × 30.7 mm: enough for a WotC clickwheel life counter.
It's a good box for a draft kit. There's enough space for a clickwheel, some
dice, tokens, and pre-sleeved lands. And enough leftover space for a sleeved up
40 card deck.