I have both the skinny and fat stainless ones in the first image.
The fat one will easily hold flashlight bulbs. It is 42mm tall, 20mm diameter outside with a wall thickness of about a half mm. So figure the ID is 19mm. I know you could put maybe 2 bulbs in here with some cotton for padding and tinder.
The skinny one is 50mm tall and 12mm outside diameter, again about 11mm ID. Probably not going to fit a bulb.
Here are the Bison short and skinny stainless together as fire and pill kits.