What’s included One diving air cylinder refill adapter (compact and lightweight for easy transport and storage with your diving gear). Function and core benefit Safely transfers air from a large scuba tank to a smaller tank, allowing you to top up pony bottles, travel cylinders, or a buddy’s cylinder in the field. Provides a reliable way to equalize gas supply without returning to shore or a compressor. Key features that matter Professional design: Engineered for secure, efficient air transfer between tanks. 0.8 cm / 0.31 inch interface: Standard-sized connection for matching large-to-small scuba tank fittings. Luminous pressure gauge: Readable in low light and remains visible to depths of up to 80 meters underwater, improving visibility during night or deep dives. Easy-to-read dial: Clear display of pressure levels at a glance to help you monitor transfer progress and avoid overfilling. Performance and compatibility Designed specifically for scuba use to transfer air between tanks with compatible fittings. Compact and lightweight for easy packing with dive kits; stores conveniently on boats or in dive bags. Durable construction intended for routine dive operations (follow standard safety and inspection procedures before each use). Practical applications Emergency air sharing: Quickly move air from a full cylinder to a near-empty cylinder to extend dive time or support a buddy. Pre-dive topping up: Top off a small travel or pony bottle before shore entry when no compressor is available. Boat or remote diving: Manage cylinder inventory on dive boats or at remote sites where full refills are not immediately accessible. Safety and use notes Use only with tanks and fittings that match the 0.8 cm / 0.31 inch interface and follow accepted scuba filling procedures. Monitor the luminous pressure gauge and the easy-to-read dial throughout the transfer to control pressure and avoid overfilling. Inspect the adapter and gauge for damage or leaks before each use. This refill adapter offers a portable, straightforward solution to transferring air between scuba cylinders while providing clear pressure readouts even in low-light, deep-water conditions.