Analog, Digital or Audible Altimeters.

Australian Parachute Federation Op Regs May 2012 state:

8.5 Visual Altimeter Requirements    
• (a) A functioning visual altimeter approved by the Manufacturer for the purpose of Skydiving, and set to indicate height above the DZ must be:
      
• (i) Worn on all descents; and
      
• (ii) Securely mounted so that it can be read without difficulty throughout the descent

Great prices on Analog, Digital and Audible Altimeters.