Replacement battery and O-ring kit for Suunto D4 and D4i Dive Computers. Includes lithium battery, O-ring and silicon grease lubricant for O-ring. Always pack a spare: You just set up your equipment for your first dive adventure of your vacation in Saint Somewhere. As you press the activation button on your Suunto wrist computer it goes through the diagnostic screen and what do you see the "Low Batt" Icon appears. The worst thing that can happen on an outing has just happened, No Computer! Don't leave on a trip without a spare battery kit. Why ruin a great day because of a few dollars in parts. If you're planning a vacation or trip this is a must have item to bring with you. Meets factory specifications and guidelines. The battery kit includes a new 3V lithium battery, o-ring grease and compatible o-ring.