Two blades in one slim frame: a clip point for piercing and detail work, and a spey for skinning and scraping. The standard Case trapper is the 6254 SS pattern at 4.13 inches closed with nickel silver bolsters, and it is probably the most recognizable American pocket knife pattern there is.
The clip point handles anything needing a point. The spey, with its rounded tip, skins and scrapes without risk of puncturing. Between them they cover most of what a pocket knife is asked to do.
Both blades pivot from the same end, which keeps the knife slim despite carrying two.
Handle material and decoration, mostly. Natural bone in various color washes, commemorative and artwork editions, and gift-boxed sets all share the same 6254 SS pattern underneath.
That is worth knowing when comparing prices: a $150 trapper and a $90 trapper are frequently the same knife with different covers.
Judge it on walk and talk, on how flush the bolsters sit, and on whether the handle material appeals. Those are the variables.
Case warrants each knife for the life of the owner. See the Case warranty.
Specifications above come from the manufacturer. Live prices and availability are in the strip below, pulled from the catalog at build time rather than typed into the copy, so they cannot go stale on this page.