Fit critical

The box is ok for the price - not burred and slightly warped. The related plastic is quite brittle, but since I only need the box for storing a short-circuit protection, it does not matter. Unfortunately, the size is extremely tight. Since 18650 are not standardized and vary slightly by various techniques common in both length and girth would have more leeway here must be. Batteries with double sheathing (eg the linked Frequently bought together here as of Kuffner) are too thick.
In addition, the flap is very narrow, so that the box is not to remain.
For unprotected 18650 but certainly useful.