The scooters within the KOS Series is Envy's top of the line models. Every model in the KOS line is made of all after market products, and has received significant upgrades. The KOS Soul uses the cromoly steel Soul bar, AOSv4 inspired deck, Declare v2 SCS fork, Omen SCS Clamp, and the Envy Tri Bearing Wheels. The combination of these parts make the Soul a pro scooter that can excel in every style of riding, but is specifically designed to be a street focused scooter.
The AOSv4 inspired deck is made of 6061-T6 Aluminum and comes in at 5.5" wide, and 22" long. This size is the largest to ever come on an Envy pro scooter, and proves Envy's dedication to both styles of riding. It also uses Envy's custom Boxed Inserts that provide a larger space to lock into grinds, and will prevent the deck from caving in due to grinding. These Boxed Inserts also only require ONE allen key to adjust, as threads are built into one of the inserts. So extremely consumer friendly, and will keep riders out of tool boxes! The steel Soul bar is one of the most reliable bars in Envy's lineup due to the material, and supporting gussets. These parts roll on the Envy Tri Bearing Wheels, which are 120mm in diameter, and 30mm wide. This larger size will yield greater speeds, and provide more clearance for the bottom, and sides of your deck. As the name suggests, Tri Bearing wheels come with 3 bearings rather than 2. The additional bearing is designed to improve impact distribution, and increase the lifespan of your bearings. Finally, all of these parts are held together by the industry's best compression system, SCS. The specific name is the Declare fork, and Omen SCS clamp. SCS is extremely easy to upkeep, and will require the least amount of maintenance when compared to other compressions. This means you'll spend less time messing with bolts, and more time actually riding. All of these parts together create a weight of 8.8 lbs.
Now who is the Soul for? I would recommend this scooter to riders who want to focus on street style riding. The scooter isn't too big or heavy to do park style tricks, but inexperienced riders may have trouble doing them. In other words, if you're not sure which style of riding you want to do, I would go with the Charge or Heist due to their versatility.