If you have ever suffered a barbecue failure due to an empty propane tank then the Refuel smart propane tank monitor is one way to go about shielding yourself from the possibility of future humiliation.
The tank uses a waterproof scale to track your propane levels, which are automagically transmitted to a phone-based app. It also includes a wired indicator that attaches magnetically to your grill in case you don’t want to check your phone to find out your gas level. All things considered it is probably overkill but would make a worthy gift for the man (or woman) who has everything. Alternatively, you could just fill up your gas bottle before important barbecues or… figure out how much your tank weighs when it is empty and keeep a luggage scale with your grill.
At any rate, it is a clever idea and $18 is a small price to pay for wireless propane supply monitoring.