This is a very reliable piece of equipment. The triact lock is positive and easy to operate with full finger gloves. Ball lock is a little more difficult and not as "robust" in my opinion. Twist lock is cool with marking to identify if locked or not. OVERALL GREAT OVERSIZE BINER.

I have got to say, out of all the biners I've own or used over the years, this is the quickest and easiest one I've seen. The Ball-Lock is great! Only having to twist about 25 degrees, rather then the 45 on any other twist lock, means I can get it open even at odd angle where I don't have an ideal grip. Making it super easy to get on and off belay. Plus the simplicity of just having to visually check for a green dot to know that the gate is locked is a real turn on for me.

This biner is a giant. I bought it to go with the Piranha but don't usually use them together. The oval cross section of the biner makes it a great fit into the device, but it means the device stands straight up even when your not using it. In a canyon thats a bit annoying. The biner however it great. Its vice looking with a soft finish thats easy on a rope. I was surprise however at the size of it. Its really a big biner. The screw gate doesn't stick much even if i forced it closed. I really recommend this if you want a big biner to rap or belay off of.

I have worked on multiple challenge/high ropes courses over the past few years and saw nearly every program make the transition to these triact biners.
1. Most of the participants can't figure out how to get them open.
2. They are large enough to handle multiple ropes (including old stiff ones)
3. Sturdy enough to handle prolonged daily use.

They take a while to get used to, but you won't be disappointed!

This is my go-to belay biner for tube devices, as it handles rappelling on even the biggest 11mm fatty singles with ease, and also makes a nice large power point biner on anchors. Plus, the round bar stock is easy on ropes and provides plenty of friction. I might go for something a bit smaller if I have to lug it up a mountain, but for cragging and gym climbing this is a great biner.

The shape, gate opening, and smooth screw-lock of this carabiner make it my favorite extra-large.

And still fairly light, in comparison to others of its size.

I have a Petzel William Screwgate locking biner as a dedicated belay and rappel biner. The Petzel William is very big and belays nicely with an ATC. It also rappels nicely with an ATC. I also like the added feature of the red, which visually lets you know if you are not locked. While there may be some marginally lighter options for belay/rappel lockers, I think the Petzel works great.

This is a great carabiner for people starting out. This way you don't have to remember to lock it up. Or is it a bad thing so that when you graduate up you'll always forget because you didn't have to do it before? Anyways high quality as always from petzl.

I bought the triact (to go with my grigri for idiotproof belaying), and then the screwgate later (for clovehitching when outdoors). Both are fine carabiners.

The triact's gate snaps shuts with a satisfying click, when closed properly. However, if closed softly and it may not lock.properly - leaving the nose sticking out of the collar. It needs that snappy momentum to shut properly.

In reality, using a huge carabiner with a grigri is unnecessary, and holding the gate open while arranging belay devices is annoying. As a result, I don't really use it anymore indoors, and outdoors it's just another carabiner.

The screwgate is much better. It's large size and flatness makes it great for clovehitching even with fat ropes. Plus, the red band around the collar alerts you to when the gate's not done up properly.

Would recommend the screwgate over the triact.

I've used both the Triact and the Screwgate versions of this carabiner.

After a lot of analysis of top-rope safety issues, I've adopted a practice of using a pair of Triact Williams for TR master points. Too many times, beiners get flipped around on top-rope, especially when climbers are topping out. With the Triact William, I don't have to worry about gate direction and the issue of it unscrewing over time. It's a virtual impossibility to hit the right combination of scrapes and loads to permit the gate to open. It's the safest master point I can come up with using standard gear.

For trad, I use the Screwgate Williams for my main anchor masterpoints. The extra clipping space is very welcome, and the key nose is a great feature because I never have to fight with the biner snagging a cordelette or a wire.

The fit and finish is also impressive ... it's a first rate piece of gear.

This is the big bro of the attache. Works just as well, but for different purposes. That clean profile doesn't catch and makes life that much easier. Well worth it. Buy a couple or wish that you had.

The Petzl William Locking Carabiner is a quite a bit larger than what I usually use from day to day. I LOVE using this biner on multi pitch rappels or climbs. Its steady and solid all day long. Its still really easy on your ropes and the triact lock is SO convenient. I use this biner a lot to set up my slackline also, its got a lot of uses and despite its size isn't to heavy or bulky feeling.