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 . The charger is sold .  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!

Dimensions:

Diameter = 1.073 inches

Length = 4.00 inches