What battery does swiss army 241499 take

Swiss army batt 20110106 1810

The only way to be sure is to get a water proof watch case back wrench off ebay - the good kind with 3 fingers and it will cost you $15 - $25. If you're into doing these things yourself the buying the right tool once will pay dividends down the road. Forget the $5.00 tool from Walmart. In the hands of a novice it will just get you into trouble. Then remove the case back and get the number off the battery. Replace with silver oxide (alkaline are available but will only last a month instead of 2-3 years. Lastly, apply a thin coat of Silicon grease to the rubber case back gasket with a tooth pick before re-installing the case back (di-electric will work if your careful running $2.00 from your auto parts store). You must be careful not to get the grease under the gasket and better if you coat just the metal surface the gasket mates with. Getting grease under the gasket coating all surfaces the gasket comes in contact with will just cause the rubber gasket to spread outwards and stretch as you tighten the case back - loosing its water proofing. If this happens, clean the gasket and metal surfaces with rubbing alcohol and start over coating just the top surface of the rubber gasket. Also, if using Di-electric grease instead of just pure silicon - this stuff is conductive, so don't allow it to touch anything inside the watch and don't use it to seal the crown stem o-ring or the hack feature will be shorted out and you'll have to get the watch serviced by a pro.

-Don't try to spin the case back off with a pear of needle nose pliers or what knot.
-Don't try to re-install the case back without applying a thin layer of silicon grease. You will destroy the water proofing - it will steam when you sweat.