I've always found it annoying to have a bunch of keys in my pocket (they're heavy, sometimes poke into you, and create weird bulges), so I try to carry as few as possible. Unfortunately, I've reached a point where I have a fairly large number of keys that need to keep with me sometimes:

• Default key chain: Apartment key, apartment key fob, USB security key, mail key
• Car key
• Bike key
• Storage keys
• Multitool (I know, it's weird that I don't always carry this, but it's heavy)

Previously I kept all of these except the storage keys on one keyring, but I recently realized that tiny carabiners exist, which means I can keep all of the non-default keys clipped to a storage area and then add just the keys I need during the day.

For example, most days I just need either my car key or bike key.

The downside of this is that the caribiner itself adds size and weight, so if I needed to carry the full set of keys it would be even worse. Luckily, that doesn't seem to happen to me (and some keys are mutually-exclusive, like the bike and car key). If you do have a large number of keys you need together, this won't help you.

The specific ones I bought were this 12-pack of tiny caribiners on Amazon, but I don't have any particular faith in this clearly-random-name-generator company. This size is perfect for the non-hook size to hold a tiny key ring with 2-3 keys. I didn't get double-caribiners because I don't have any need to quickly detach the keys themselves, and that would make them slightly bigger.

I thought this might be a place where other people who care unusually-much about the exact weight of their pockets might congregate, so if you feel similarly, consider getting some tiny keyring carabiners.