Nicholas Comtoiswrote a review of Black Diamond Bullet 16L Backpack on September 5, 2016
Familiarity: I've used it several times
I was envious of a friend's previous generation Bullet Pack, so when it was time to decide on an on route pack to carry essentials on all day multi pitch routes the Bullet was in my top three packs to consider.
The size (16 liters) is just large enough to fit the essentials, a shell, water, phone/keys, and a snack for instance. It's small enough that it basically goes unnoticed while climbing and sits high enough that it doesn't get in the way of grabbing gear off your harness.
The pack is very svelte, so there's not a lot to get caught on rock or gear. The materials, like the burly over sized zippers, and bombproof face fabric, are meant to take a ton of abuse. The hip belt is a straightforward nylon strap which I feel is adequate, it's also easily removable, and stowable. The shoulder straps are wide and well padded for the size of the pack and fit a larger chest very well. The should straps and hip belt stow easily in the back panel of the pack so that it can easily be hauled up chimneys without getting caught on anything.
Other features include a removable foam back panel, a small exterior pocket, and a small interior mesh pocket inside the main compartment with a key clip. There's also a hydration port. This pack does not have loops or any attachment points on the outside aside from the top grab/haul handle. If you're looking for a small on route pack that will also carry your rope on top or one you can lash gear to look elsewhere.
If you are looking for a purpose built, streamlined, and tough-as-nails on route pack, look no further. You'll enjoy it so much you'll want to use it as your everyday around town pack.