The Meritor A2258J1778 or A-2258J1778 is a genuine OEM air spring covering all low mount models. Air springs are load-bearing suspension components that replace conventional coil or leaf springs in heavy-duty truck suspension systems, maintaining ride height and absorbing road shock under variable load conditions. This part, for fitment on low mount applications, is sold under the Meritor brand, which was formerly associated with Rockwell. Call us to confirm compatibility with your specific suspension configuration before ordering.FeaturesGenuine Meritor OEM air springPart number A2258J1778 or A-2258J1778Designed for all low mount suspension modelsReplaces conventional springs in heavy-duty truck air suspension systemsSold by Pro Gear and Transmission