FWIW mag lights come with a spare bulb in the base, under the spring.

I also have a light intended for my bike. It has 2 high output quartz bulbs and a water bottle sized and rechargeable battery. The battery is connected to the light fixture by way of a 3’ long cord. The battery lasts about 4 hours with either bulb running. I sometimes use it when backpacking. I think it’s called a cryo-light

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...Tracy

'00 ML320 "Casper"
'92 400E "Stella"