Great Grips are easy to install. The soft material easily stretches to fit the knob. The material becomes even more flexible after immersing it in hot water for 10 seconds. With normal exposure to sunlight, the "glow" crystals will be visible for 6+ hours. Recharging with sunlight will enable the "glow" crystals to continue working for the lifetime of your Great Grip. For $2 more, you can add the antimicrobial power of AgION TM to the standard model. Shipping Rates: Shipping is based on weight and is approximately: 1 2-pack $2.25 2 2-Pack $3.00 Money-back Guarantee: If you are not satisfied with your purchase, for any reason, please return it within 30 days for a full refund.