Popular Timbren SES kits were designed to work on pickup trucks with a standard ride height. But installing a lift kit on your pickup truck will increase the distance between the frame and the rear axle and, therefore, compromise the effectiveness of the Timbren SES helper springs. In other words, your lifted truck is still going to squat even after a Timbren SES rear kit has been installed. That's where an approved Timbren spacer kit can fill the gap. This spacer kit will enable you to haul your gear with confidence even if your lifted Chevy Silverado 1500 or your GMC Sierra 1500 has approximately 5.75" - 7.25" of space between the frame and the rear axle. Here's how it works: Each spacer kit comes with two 1 inch and two 1/2 inch spacers along with all the necessary hardware. This handy little kit helps you mix and match the spacers when you add them to the Timbren SES assembly allowing you to achieve your desired ride height. Whether you've got a leveling kit, body lift or full suspension lift, Timbren spacer kits allow you to make effective use of your Timbren SES kit while hauling or towing your gear. How Do I Know If I Need a Spacer Kit? To determine whether you need a spacer kit, measure between the frame and rear axle of the truck when empty. If the gap between frame and axle for your Chevy Silverado 1500 or your GMC Sierra 1500 is approximately 5.75" - 7.25" you will need to order a spacer kit.