Dual-Pour Construction - Two bands of urethane combined to optimize every category you want in a hockey wheel; Grip, speed, and durability. The inner band of urethane is slightly softer than the outer, this allows the harder band to take the brunt of wear and the softer band to flex and rebound. Super High Rebound Urethane - Super High Rebound (SHR) urethane is the standard in premium hockey wheels. Rebound describes the wheels ability snap back to form after compression. Rebound plays a significant role in the amount of speed, grip, and flex of a wheel. 74A - An extra soft hardness. Grippy out of the box and will release and slide with enough pressure. Ideal for 185lbs and under on smooth surfaces like sport court and wood. Not recommended for outdoor use. This configuration features 2 hub styles. The 72mm hub is unexposed while the 80mm hub is a 5-spoke. The unexposed hub style of this wheel makes it agile and grippy. The 5-spoked hub style of this wheel contributes to a light-weight and durable wheel. Each features 12 inner hollows which ensures a hard bond between the urethane and the hub. No matter the size, the hub style leaves ample space for urethane flex which allows the wheels to dial-in and maximize grip. Amp Hybrid Ceramic bearings are like stimulants for your wheels. With this bearing you get the precision of ceramic and the durability of steel balls. The single Ceramic ball cleans debris and cools friction allowing for a longer lasting bearing. Includes: 4 72mm Wheels, 4 80mm wheels, 16 Hybrid Ceramic Bearings, 8 8mm Floating Spacers, and 8 6mm Stepped Spacers (You only need 1 set of spacers based on your skates, we inclue both as a courtesy). This configuration is common on older hockey skates, make sure to confirm the front wheel size is 72mm. Skates use different wheel configurations, most use one of these 5 basic sizes: 59,68,72,76 or 80mm. Measure your current wheels, or check your skate specs to ensure a smooth installation!