Help with battery ID please

I picked up two little single cell “power banks” in a thrift shop a few days ago for a buck apiece. They were new and unused, still in bubble wrap. Of course, I immediately popped them open to see what was inside. They have a mini USB charging port and a standard USB outlet.

The 18650 cells are flat topped, 65.2 mm long and appear to have protection circuitry. They started off at 3.6 v. and charged nicely to 4.2 v. after I rigged up a suitable charger.

Each has a single deep purple/plum coloured 18650 with markings that I can’t seem to identify:

BF 18650 ICRRJ
KPYNLA31A16

I’m assuming this is ICR chemistry, which doesn’t do much for my peace of mind, but I’d like to identify them before I put them in the recycle box at the local electronics shop. Mainly I’m curious about the manufacturer, the age, and the discharge capacity.

Can you show us a picture?

What color is the insulating ring? The purple wrapper could be anything. Not familiar with the coding either. Picture please.