Nitrous Supply just released what they are calling the Power Valve for all nitrous applications. It is equipped with a safety pin that is spring loaded to prevent accidental bottle opening as well as many other features.

Official Release

SAFER, HIGHER FLOW NITROUS BOTTLE VALVES FROM THE LEADERS IN NITROUS

The Power Valve from Nitrous Supply was an immediate hit with hard-core racers when it was released. The Power Valve’s revolutionary design offers maximum nitrous flow with none of the bottlenecks or restrictions normally associated with bottle valves. The on/off lever lets you know whether the valve is open at a glance even in low-light conditions aiding in real-time situations at night races. Additional safety features include a spring loaded safety pin that prevents accidental bottle opening. 
This valve is the latest in innovations brought to you by Nitrous Supply, and its President, Mike Thermos, one of the original founders of NOS. 
If You Are Serious About Making Big Power With Nitrous,
This Is Your Next Purchase.

• Highest flow rate of any valve on the market
• Quick, 1/4 turn for full on or off position
• Over twice the flow of super hi flow valves
• Fits 5-20 pound bottles and carbon fiber bottles
• Spring loaded safety pin (prevents accidental opening)
• Accepts extra large 5/8 threaded siphon tube
• Two 1/8 NPT gauge ports
• Racer safety blow off
• Large -8 outlet
• 6 adapters included