The heart of the HTV371 system was its Hydrocarbon-fueled Scramjet engine. Unlike rockets, which must carry heavy liquid oxidizers, the Scramjet acts as an "air-breathing" engine, scooping oxygen from the atmosphere to combust fuel.

: Reviewers note the "371" pack provides a high-shine finish suitable for making unique custom apparel. It is designed for use on any material that can withstand a heat press, such as cotton or polyester.