The Vapor 4 is built around a 3D air mesh main chassis with PWR | Shell ripstop stretch fabric over the impact zones. Knee armor is included (Seesoft CE-Level 1) with a Level 2 upgrade available; hip armor is sold separately, which is the usual Rev'It pattern and a frequent complaint.
Airflow is the whole point: riders consistently report the Vapor 4 as the closest thing in textile pants to wearing nothing, while still passing a basic abrasion test. That's not the same as wearing leather — these are not track pants — but they're rated as a competent street pant that won't kill you on a low-speed slide.
What riders like: the cut is sportbike-friendly, with extra room in the thigh and a tapered ankle that doesn't bunch on the boot. The connection zipper at the back is compatible with most Rev'It jackets and several other brands' zippers. Fit runs slightly long — most US riders go one size down from the size chart's recommendation.
Caveats: don't expect rain protection. These are mesh; water passes through. Rev'It's pattern is to make separate adventure-rated pants for wet weather and let the Vapor line own the heat-of-summer slot. The lack of included hip armor at this price point is the persistent gripe — budget another $40-60 for the Seesoft hip inserts.
Versus Dainese Tempest 3 D-Dry pants: the Dainese is waterproof and warmer; the Rev'It is dramatically more vented and lighter. If you ride summer-only in a hot climate, the Vapor is the answer. If you ride year-round in mixed weather, the Tempest makes more sense.