Evva is a company that adds a protection circuits. Same as keeppower, xtar, orbtronic, EagleTac etc. Evva does Panasonic cells (plus all other top brands) and they use seiko chips and quality mosfets. I mentioned Evva because they seem to do quality protection for the lowest cost.
So here “Evva” just means the same Panasonic cell but with seiko quality protection (and someone willing to add their name behind it instead of all the clear wraps).
Evva protected Panasonic NCR18650B 3400mAh - mtnelectronics usa $9.65
Evva protected Panasonic NCR18650B 3400mAh - banggood $10.99
Evva batteries in bulk for resellers
BLF Evva teardown Protection PCB picture and comparison to keeppower Evva vs. Keeppower NCR18650B Protection PCB Visual Comparison