This is the Oceanic Swivel Hose Mount Compass for Scuba Diving Features: Proprietary design ensures quick response and smooth movementTop or side reading OceanGlo luminescent floating card absorbs light and glows approximately 7 times faster and longer than other materials High visibility lubber lineLarge ratcheting bezelDirect and reciprocal index points This convenient hose mount compass module is your best choice. Allows diver to choose when navigation is required by using a durable rubber boot with threaded adapter that clamps quickly and easily to any high pressure hose. Boot has side scan notch for side-reading gun-sight accurate navigation.