The 870 Express combo usually comes with a 28" barrel with interchangeable choke tubes and a ventilated rib (helps with heat dissapation and acts as a sighting rib) for hunting birds and the like. The shorter barrel (usually about 20") may have a bead or rifle type sights for use with slugs or buckshot when hunting deer. As to the cost, if it's a standard Express (not the "Super Magnum" with a 3 1/2" chamber) I think they usually go for about $500.00 at places like LeBarons (I don't have a current catalogue but I'm sure someone on the board will tell you the exact price and question my parentage in the process). The one at $635.00 may well be a reasonable price if it's got upgrades, you have to compare apples to apples. Hope this helps.