Desk Pen Sets: This Altimeter Desk Pen Set is an alarm clock and pen set. The desktop alarm clock and pen desk accessories are a fun and useful aviation gift. The Altimeter Desktop Alarm Clock is an authentic replica of the altimeter instrument found in an airplane cockpit. The alarm clock has luminous hour and minute hands and also a second hand. It has a durable polystyrene case with glass cover measuring about 3 ¼" high. The clock has quartz movement and a “AA” battery is required.