The following options are available: Upgrades Closed Circuit Nitrox + 49.00 Open and Closed Circuit Nitrox and Normoxic Trimix + 146.00 Open Circuit Nitrox and Normoxic Trimix + 97.00 Standard Open Circuit Nitrox You can choose options in your basket. Colour screen version The VR computers are the most up to date computers on the market and we aim to keep them right there on the cutting edge of technology by adding useful options and fun features all the time. They are truly dive computers for the 21st century, interactive tools which meet the needs and match the lifestyle of those of you who are used to the advantages of mobile phones and PDAs in your surface existence and want similar technology to accompany you on your underwater adventures. User-changeable AA battery either 1.6V alkaline or 3.6V lithium Easy-to-open battery cap with purpose-built key External Switches mean the computers are fully programmable underwater Variable light settings Right / left wrist mountable, You can install up to 10 pre-set gases in the VR3ﾒs gas list; air, oxygen or any nitrox, trimix or heliox mixture. In the VR2 you can install up to 4 gases, air and nitrox mixtures only. The VR2 has a gauge mode so it can also double as a bottom timer.