This is a Panasonic lithium manganese rechargeable coin cell with a pre-fitted two-pin JST plug and an adhesive mounting pad. Designed for use as a long term battery backup for Raspberry Pi 5 computers.
Adafruit NeoPixel Digital RGB LED strips come to us in 4 or 5 meter reels with a 2 or 3-pin JST SM connector on each end and separated power/ground wires as shown in the picture below. If you order a full 4 or 5 meters, you get the full reel with both connectors installed.
If you buy less than a full reel, you'll get a single strip, but it will be a cut piece from a reel which may or may not have a connector on it. If the piece comes from the end of the reel, the connector may be on the output end of the strip!