The Black Diamond Angle is the most classic piton still made and is the image most people associate with a piton. It's amazing to think that at one time routes were mostly climbed on angles alone. Now they are far less necessary, even on nailing routes, because they cover a size that most small cams and offset nuts work with. That said, you still need a couple on your nailing rack and sawed angles may be necessary on some trade routes like The Shield (even if you are mostly hand placing them).
Black Diamond Angle Review
Cons: Easy to drive too hard, damagingrock when being cleaned; usually you can get a clean placement instead
Manufacturer: Black Diamond
Our Analysis and Test Results
Angles have a design that causes them to both compress and expand when hammered and grip the rock. This means that even when you don't hammer them hard, they can hold body weight. They can often be hand placed in pin scars if you are doing cutting edge clean aid. They are relatively light when compared to a piton like the Black Diamond Lost Arrow.
This gives them extra holding power in cracks and this is the piton you most often see fixed on routes. It's tempting to over-drive them, which makes them very damaging to clean because you end up hitting them back and forth a lot. One bummer is that on the 3/4" and 1" sizes they don't come a little shorter. Sure that long size might have been good back in the day. But today, you generally only need short piton in that size. That means that you usually need to saw of the pitons yourself with a hacksaw and the round the edges.
You need a couple of these for most routes. The are great in tiny little pods where a cam won't fit. They can also be the only thing that holds in wet rock. That said, often a cam like the Metolius Ultralight Offset Master Cam will work in a piton placement or piton scar even better than an angle (and won't damage the rock).
These are a good deal when compared to the much more expensive Black Diamond Lost Arrow.
— Chris McNamara