You just set up your equipment for the first dive of your vacation in Saint Somewhere, as you press the activation button on your dive computer it goes through the diagnostic screen and what do you see the "Low Batt" Icon appears. The worst thing that can happen on a tropical vacation has just happen No Dive Computer. Don't leave on a vacation without a spare battery kit, why ruin a great holiday because of a few dollars in batteries. If you own a Oceanic OCL Computer, you don't want to go diving without this battery kit. The kit includes battery, O-ring and silicone lubricant, a must addition to any diver's save-a-dive kit. The Battery is a 3.0 volt CR2430 lithium ion cell. Kit includes battery, hatch O-ring, silicone grease and instructions for battery replacement. Battery is sold as a single and can save-a-dive when you need it most. If you're planning a dive vacation this is a must for your save-a-dive kit. Avoid island prices with a fresh batteries!