This is the Aqua Lung Low Pressure MP Braided Inflator Hose 3/8in 

Features:

• Braided Advanced Technology
• Flexible & Durable
• Light Weight BCD Hose
• Standard 3/8-24 UNF Male Threaded
• Available-In Multiple Lengths
  

These braided Low Pressure Inflator hoses are what you'll need for your regulator to connect to a BCD. Choose from 3 sizes - 22", 25" and 27". You're average sized diver will use a 25" hose, so based on your height, go up or down a size.