Until recently, when it came to bike locks, you had to make a choice between weight and security. Good U-locks are quite secure, but they are heavy. Cable locks are flexible and light, but not very secure.
The folks at TiGr decided to make a secure lock out of titanium. Titanium is strong and flexible. Their first lock was a bow designed to lock both wheels of a road bike. Of course any lock can be broken given enough time and big enough tools and the initial version of the lock with a .75 wide bow could be defeated with a large set of bolt cutters. Their current bow lock is 1.25 inches wide and has been extensively tested and ART certified. Of course, no lock is 100% theft-proof but from what I've seen the TiGr locks provide a level of security on par with a good U-lock.
While the bow design works well for various bikes, I was more interested in the TiGr mini, a small lock quite similar to a U-lock.
Here's my old, very reliable ABUS U-lock:
I have no real complaints about the Abus lock, it's been very reliable. It also weighs a bit over three pounds.
My TiGr mini lock weighs a bit under one pound.
I use the TiGr mini much the same way I used the Abus, with a flexi cable to secure the front wheel of my bike (yeah, I know, someone could cut the cable. But there isn't a huge illicit market for 20" wheels, so so far, so good). And the lock itself is just big enough to secure the rear wheel via the Sheldon Method. If you have a fat-tired mountain bike the TiGr mini might not be big enough, but for a road bike or something like my Bike Friday, it's just about the perfect size.
The lock mechanism itself has a very smooth action and it comes with two keys. Like most good locks, you register it with the company so you can get a replacement key if you ever need one.
The lock comes with a very nice bracket that I don't use. The bracket takes up a waterbottle spot and with every lock I've ever had, I never use the bracket. I always just toss the lock in a pannier or pack or strap it to my rear rack. But if you're the type who uses a lock bracket, the TiGr folks make a good one.
The TiGr is made by a small, family owned business right here in the USA. Yes, the lock cost about twice what my old lock did, but I consider it money well spent. BTW, yes I bought this. I get industry pricing because I work in the bike biz, but like you, I buy stuff. Nobody is paying me to say nice things. But this is a nice thing.
Oh, and if you do buy it through the Amazon link, I do get a kickback. Bottom line, it's a good, secure, lightweight lock.