Another brilliant innovation from a UK military tailor - Handmade UK
Ditch the resealable poly bag / sniper tape bundle with your spare headtorch batteries and swap it out for one of these waterproof, ripstop battery pouches. Drop your spare batteries into the pouch, roll the top down (like you would with a full sized dry bag) and then secure the bag closed using the one-wrap velcro band. For added "Allyness", wrap the band around your headtorch strap/attach it to your helmet so that you've always got a spare set of batteries ready to go!
Suitable for 3 x AA or 4 x AAA (or equivalent sized) batteries. Ripstop construction with taped, waterproof seams (batteries not included)