When shopping for loppers you’ll find two types of cutting heads: Bypass and Anvil. While standing in the aisle looking at the options and the marketing terms used to describe them you will not be able to determine which is better for your situation. Here’s the deal:
Bypass loppers make clean cuts in green material. If all you’re doing is cutting live branches, and you want to make the resulting wounds easy to heal, bypass is your tool. Also, if you use bypass loppers for live branches, the blade will never run into anything capable of marring it and it will stay sharp for a very long time. Maybe even forever. However, if you use bypass loppers on dead branches, they will require lots of extra force and become dull quickly. Also if you use too much force with tough material, the blade may gradually get pushed away from the holding jaw and you’ll experience an annoying ‘loose scissors’ effect where the bypass loppers are just pinching branches sideways between the jaws without cutting them.
Anvil loppers make brutal cuts in anything: they don’t care about whether the branches are live or dead, but the wounds from live branch cuts will have some crushing involved, which is said to make healing more difficult. By design, anvil loppers smash their blade into a soft metal ‘anvil’ and eventually this metal-to-metal collision will make the blade dull and it will need sharpening. The blade is straight though so it should be fairly easy. And the anvil is replaceable in case it gets grooved. Anvil lopper jaws come together dead-center so they’ll never experience the ‘loose scissors’ effect mentioned above.
In conclusion, if you will be cutting a mix of live and dead branches, you will find the anvil lopper is easier to use and longer lasting. If you’re only interested in cutting live branches, bypass loppers will be easier on you and your targets and may never need sharpening.
Another thing you’ll see promoted is ‘compound’ (or ‘gear driven’) cutting action. Whenever you’re cutting something 3/4″ or bigger in diameter, this feature will make the cut dramatically easier. You may have encountered the situation where you have to repeatedly shock-load the handles of the loppers to get through a tough cut, and it may feel like you’re close to bending something in the process. If so, compound action is the way to go.
Update: after using these Fiskars bypass loppers on many green branches and a handful of small dead branches they have gotten some blade wear. They still work fine for branches but are no longer sharp enough to cut the thick grass of the yucca.