Let me tell you, these GoodBoy 6V batteries are the unsung heroes of my dog-training journey. My Labrador, Max, used to bark like he was getting paid for it – until we got the GoodBoy collar. But man, those original batteries drained faster than my patience during his 'midnight concertos.'

The moment I popped in the first replacement from this 5-pack? Magic. No more frantic Walmart runs at 9 PM when the collar dies mid-training session. Each battery lasts about a month with Max's enthusiastic vocal performances (3-4 barks per squirrel sighting). At this price point, I'm basically saving enough to buy extra treats!

Bonus discovery: These fit my vintage Canon AE-1 camera perfectly! While they only lasted two film rolls (about 2 weeks), that's standard for this camera type. Just don't be like me and forget them in the camera – they will drain.

The packaging deserves applause too – sturdy enough that my toddler couldn't destroy them (unlike my last Amazon package). I keep extras in my training bag, car glovebox, and junk drawer because you never know when your neighbor's new puppy will trigger Max's protective instincts.

Watch out though: Some reviewers mentioned receiving different brands than pictured. Mine were correct, but maybe check recent reviews before ordering. Also, remember to physically remove batteries from devices when not in use – these don't have an off switch!

Final verdict? For bark collars, these are golden. For other devices? Solid budget option if dimensions match. Either way, keeping this 5-pack on subscribe-and-save has saved me countless 'dead battery emergencies.'