Checkers Industrial Safety Products BPRO-G Beacon Pro LED Flare Alert Magnetic Base, Green

this is an ideal marking device, its powerful magnet holds tight, very tight. Only downside is difficulty changing batteries. Thankfully that's not too often

This thing is blindingly bright, but the execution of the design is stupid. They put a small, rubber gasket where the top and bottom screw together to make it water resistant, but the button to turn it on is not water resistant at all? Water gets inside and then the item won't work. So....if you need a road flare for indoor use it's great, if you tend to need road flares outside, like I would assume you do, then I would buy something else.I see another review stated there is a rubber cover over the on/off button. Mine did not have this feature.