Most of the pistol type marketing junk sold at very low in cost in marine stores may get you past a USCG inspection but offer little help at night calling for help. The altitude is too low, with too little lumens, for way too short of time. If you ever want to call for help you should have a number of SOLAS devices coupled with at least one waterproof handheld VHF.
Flares that work when your life depends on it!
There are also a number of YouTubes on how to convert your cheap flare pistol into a actual handgun. Shoot you flare pistol next New Years or 4th of July then throw it away and get some proper marine signal devices.