2" overall. Clip. Keychain. Glows for up to 10 hours. Battery free. Recharges by sun or light source. Markers help to be seen while walking at night and make it easier to find things in the dark. Attach to tent, zips, backpacks, keys, phones, clothing, animals, or anything you may need to find in the dark. Suitable for scuba diving up to 25m or for use during night fishing.