Extra Visibility Allows 12 Foot Clearance between People and Launcher The new, larger pressure gauge is 3-1/2" in diameter. To increase safety, this gauge is easily legible at a distance of twelve (12) feet. Twelve (12) foot hoses are important to keep people at a distance when the water rocket when is pressurizing. OLD soda bottles are not as strong as new bottles, and there is a higher chance for older bottles to burst. When standing at a safe 12 feet distance,the rocket launching person can easily read the numbers on this large pressure gauge.