Lock - Abus Phantom cable
It's a key-lock made by ABUS, a famous German lock maker and the inventor of the U-lock (not, it wasn't Kryptonite or Citadel).
The Phantom is a key-lock (comes with two keys), made of thick cable covered with hardened steel scales, covered by rubber. Grant's favorite lock by far. It's a thick and twistable/compactable lock that can fend off anything short of a bolt cutter. It's 10x easier to use than a U-lock, fits around things way better, and there's no fussing with which end of the shackle to put in which hole. A good choice for a downtown daytime lock.
Weighs a pound and a half, fits around poles and medium-sized trees. Fast, easy, good enough for daytime low-crime areas.
Go to lockitt.com to order replacement keys.