A keypad for the unit's internal computer was located in the joint coupling the two components. Buttons on the left of the keypad allowed a user to set the weapon to stun, disrupt or dematerialize, while the right side programmed in wide or narrow-beam settings. The middle of the pad included a trigger, in addition to the one built into the hand grip on the power-pac. To the rear of the top of the weapon a white knob housed the weapon's dilithium crystal and could also be used to adjust the beam-width. (TOS reference: Mr. Scott's Guide to the Enterprise; Star Trek Fact Files Issue 60-2E: "Pistol Phaser: 2271")