Scubaroo
Contributor
Don't forget that a "backup" light is for many people just that - a backup light that is guaranteed to work and get you out of the fan if your primary dies. Cheaper lights are fine for recreational scuba.
For technical diving, as the original poster asked, where wrecks or caves may be involved, I would not rely on a $20 backup. The o-rings on many commercial lights are very thin in cross-section compared to the beefy o-ring(s) on the Scout type lights. I've had commercial lights flood, but not the delrin type, and I apply even care and attention to all of my gear.
But the UK SL4s are nice for the money
For technical diving, as the original poster asked, where wrecks or caves may be involved, I would not rely on a $20 backup. The o-rings on many commercial lights are very thin in cross-section compared to the beefy o-ring(s) on the Scout type lights. I've had commercial lights flood, but not the delrin type, and I apply even care and attention to all of my gear.
But the UK SL4s are nice for the money