If you're short on pocket space, but heavy on keys, Thin Is Key (also known as TIK) might be the solution to your problem.
In the war for pocket real estate, few items are as cumbersome yet essential as keys. Touted as "the world's thinnest and lightest keychain," Thin Is Key will make sure that even if you had as many keys as a medieval dungeon master, you'd still be able to maintain the same amount of thinness as when you had only one key. Since they're made from all-metal bicycle chains, Thin Is Key remains incredibly light but still durable, and with plans to use recycled bicycle chains in the future, Thin Is Key is poised to be eco-friendly as well.
Though not for everyone, Thin Is Key is perfect for those who appreciate elegant craftsmanship and a lot of pocket space.