Diameter: 26mm / 1.02 inch; Length: 61.5mm / 2.42 inch. Material: Plastic; Color: Clear; Package Include: 4 Pcs x 18650 Battery Sleeve Tube. These sleeves are very useful to increase the diameter of 18650 battery, to be better fit flashlights that are of a tube diameter that are able to fit 3 AAA batteries. These are good replacement gaskets to use with the 18650 battery in the LED flashlight. This sleeve prevents the inner wall of the flashlight from impact with the battery to protect the battery.