Model #530 The ultimate key fob for boaters! When keys fall in the water, Key Buoy self-inflating key ring opens up, releasing an air tube which inflates automatically. Within 30 seconds, your keys rise to the surface, and the 14" (47 cm) inflated tube extends above the water, allowing you to reach over and pick them up. Davis Key Buoy (.pdf)
Strong enough for items weighing up to 2.8 ounces (80 grams) such as keys, small tools, deck plate keys. Suitable for single use only, so keep a spare on hand!