Huge weight reductions. Custom made, so anything is possible. Made for all m4s platforms and some others. Ask about your specific model. The barrels are made from a machined aluminum base and 14mm threaded tip, with a carbon fiber tube for the middle section, allowing a strong mounting base, while replacing metal on a traditional barrel with carbon fiber, which weighs only a fraction of that. The handguards use an aluminum barrel nut, and mount to any m4 platform, and can be made with cutouts, rail segments added, or even an end cap, threaded to accept accessories such as a tracer unit. Prices for barrels range from $80-110, based on length, diameter, and color. Handguard prices range from $80-150 depending on length, cutouts, rail segments, and end cap (only for ssg-1 style handguards, which I do as well) Free shipping.