Check depth easily / Check depth easily

This is a sounding rescue equipment which combines magnifier,tape and lifebuoy. You could throw it by grabbing the edge of the life buoy which simulates the shape of UFO. When this rescue equipment is dropped to the water, the tape would be released to the bottom of the water when the gravity ball is shocked. You would get a visual measure which is enlarged by the magnifier. When urgent situation, the lifebuoy could be disboarded to rescue.