This the Malkoff Devices MD21700 Body and Switch. The body is constructed of 6061 T6 Aluminum and is Hard Anodized Type III HA Black. It is fully O-Ringed for weather tightness. The removable tailcap utilizes a McClicky forward clicky switch with momentary function.
This body is compatible with the Hound Dog 18650 Head, Wildcat 18650 Head, MDX Heads and High/Low Switch Ring. It will accommodate one 21700 protected lithium cell, such as the KeepPower 21700 battery sold HERE. The charger is sold HERE. It will not fit other brands of flashlights or other battery combinations. An unprotected cell will fit, but will require possibly require a spacer to take up the extra space.
Please Note that the 21700 Battery is Longer than an 18650 and MAY NOT Fit Your Current Charger!
Diameter = 1.073 inches
Length = 4.00 inches