Will it fit my Husqvarna 455 Rancher?

Yes. The 455 Rancher runs a 20-inch bar with 3/8-inch pitch and .050-inch gauge, which is this chain's spec. Check your bar's stamped pitch, gauge and drive link count before ordering.

How is it different from a generic chain?

It is a genuine Husqvarna part, so the drive links, cutters and rivets match Husqvarna bars and sprockets. Generic chains can fit but often stretch faster and need more frequent tensioning.

What do the numbers 3/8, .050 and 72 mean?

3/8 inch is the pitch, the distance between rivets. .050 inch is the gauge, the width of the drive link that sits in the bar groove. 72 is the number of drive links, which must match your bar length.

Does it come with a bar?

No. This is the chain only. It is a direct replacement for a worn chain on an existing 20-inch bar.

Can I use it on a 18-inch bar?

No. A 72-link chain is cut for a 20-inch bar. An 18-inch bar needs fewer drive links, so the chain will not fit.

How often should I sharpen it?

Sharpen when the cut stops pulling straight or the chips turn to dust, roughly every tank or two of hard cutting. A file guide matched to 3/8-inch pitch keeps the angles right.