Loppers are used to cut medium-size branches - branches that are too big for hand pruners and too small for a pruning saw. Loppers are basically hand pruners with longer handles. Their strength comes from the extra leverage afforded by the extra length. Loppers can also have a gearing mechanism which further increases their cutting power.
The blades on a lopper will have either a bypass or an anvil action, with the best blades are made from carbon steel. The anvil mechanism, with a single straight blade meeting a flat anvil, gives a cleaner cut (with less risk of infection) but some users find that the branch slips off the anvil.
Because the lopper is a powerful cutting tool, the handles should have a rubber coating on the handles to absorb vibrations. Twisting the handles, to impose a breaking strain on the twig, is likely to damage the cutting mechanism.
Geared anvil loppers