The Ultimax 100 is a Singapore-made 5.56mm light machine gun, developed by the Chartered Industries of Singapore (CIS, now ST Kinetics) by a team of engineers under the guidance of American firearms designer L. James Sullivan.

The weapon's non-reciprocating cocking handle is located on the left side of the receiver and occupies the forward position during firing.

The overall design allows the bolt carrier group to travel all the way back without ever impacting the rear, instead stopping gradually along the axis of movement against the resistance of the return springs.

A comment to the author by an experienced SEAL team leader aptly underlines the importance of having an accurate light machine gun: "Men react one of two ways when they are shot at.

[1] An unusual feature among modern machine guns is the fact the Ultimax was purposely designed to feed from magazines as opposed to belts.

The Ultimax 100 uses a manual safety mechanism that consists of a lever installed on the left side of the receiver (just behind the trigger) with two possible settings: "S", indicating the weapon is safe, and "F", continuous fire.

[1] The system was modified to use only STANAG compatible magazines in the Mk 4 version of the design, which was submitted for the USMC Infantry Automatic Rifle competition.