Perfect for nitrous, CO2, fire, and fresh air bottles. May be mounted on tabs or flat surface. Accepts Pro-werks Bar Mount for clamping on round tubing. Micro-polished 6061-T6 billet aluminum is CNC machined for accuracy with a lightweight, attractive design. Mounts have smooth radiused outside corners and two 1/4-20 threaded mount holes with 2-5/8 spacing, measures 1/2 thick. The easy spin knob provides positive, secure clamping and quick bottle loading. Mounts are required by most sanctioning bodies and two mounts per bottle are recommended. The diameter listed is the actual bottle diameter. The clamp range is minimal - less than 1/16. To ensure proper fit, measure bottle before ordering.