Regardless of what types of dive lights you choose, the principles of using and caring for them are the same.A dive light is as much a part of your scuba equipment as your buoyancy compensator (BC) and regulator. And every piece of equipment requires diligent care and maintenance to function reliably for an extended period.At the same time you inspect your primary gear in preparation for diving, make sure to include your dive lights. Open the light and check the user-serviceable O-rings, usually found around the battery compartment cap and perhaps the bulb compartment. They should be free of debris and nicks or cuts. If specified in the manufacturers material, apply a small amount of silicone grease until the O-ring is shiny but smooth.Work the switch and lock to confirm that it moves freely. Insert a fresh set of alkaline batteries or fully charged rechargeable to ensure a strong beam throughout the dive. Test the light to make certain youve put the batteries in the correct direction and the bulb is good. Lastly, attach a lanyard or strap to fasten the light to your wrist or gear so it wont be lost in case you drop it.During the dive avoid dragging the light along the sandy bottom or banging it on hard substrate. Even if you have the light strapped to your wrist with a lanyard, carry it in one hand to prevent it from swinging free.Afterward, soak and rinse in fresh water as soon as possible. With the light in the fresh water, work the switches to dislodge trapped particles. Dry the light out of the sun. Dont open it until it is completely dry and you are sure no water can splash inside. Remove the batteries for recharging or replacement and store with your other scuba equipments.