Hourglasses measure the passage of time and have to vertical glass bulbs that connect allowing a material to trickle to the bottom. The usually contain a decorative sand but other materials such as egg powder and powdered marble. Hourglasses were very popular on board ships, as they were the most dependable measurement of time while at sea. Seamen found that the hourglass was able to help them determine longitude, distance east or west from a certain point, with reasonable accuracy. Nowadays they are ornamental or used in board games. This keychain is 100% brass that comes on a swivel brass chain with a screw lock carabineer. You will never have to worry about not finding your time for your favorite game again.