Digital altimeters are quickly becoming the standard for today's modern sport skydiver. Unlike their analog counterparts, most modern digital altimeters are accurate within 15 feet. In a sport where every foot counts and miscalculation can be catastrophic, a digital altimeter is a solid choice!
Visual altimeters are to be worn in a highly visual location during freefall to give the jumper an accurate readout of their altitude in relation to the ground in the landing area. A skydiver can choose between an analog or digital altimeter. An analog altimeter works off of barometric pressure. They are generally accurate to +/- 200 feet. They do not require batteries and maintenance is minimal.
Audible altimeters are worn on or inside your helmet to give you audible warnings at varying altitudes.