The KS3 version offers the greatest speed, power and durability. While the KS2 version allows you to get started on a smaller budget, you always have the option to upgrade to the KS3 Spring at a later stage.
Choose the Freestanding Cobra Bag if you want to get started quickly on any carpeted, tiled or wooden floor (includes Platform Paddles and Sandbags). Choose the Core Only Cobra Bag for alternate grounding options, such as making a custom baseboard, bolting the base to the floor or using Suction Cups.
Make sure to browse the Parts & Accessories section and add anything else that you might need prior to checking out.