Sidearms & Scatterguns Heads up; shotgun lights

Not sure why, I bought a total of 3. Maybe change 1 for the streamlight (then sell it) probably not! 1 guy at work wants 1. There are over 100 on eBay from $20-$99 right now.
$49 was the regular price. On the clearance shelf marked down to $24.95, but rang up at $14.95
 
so.....how well do they work?.....how do they compare to the SL?
All I've done is watch YouTube reviews, which all seem to be positive. 900 lumen vs the SL 1000. I don't want to compromise the packaging seal.
I work with 2 guys that have an 870 & a 500, that would leave me 1 Mossberg = reason to buy a 500 for my son's Christmas??