These air suspension bags are aftermarket ones. They will replace the original rear air springs. Please make sure your part number matches with one of the numbers below. Reference OE/OEM Number 251 320 0025 , 251 320 03 25 , 251 320 0325 , 251 320 04 25 , 251 320 0425 , 2513200025 2513200325 , 2513200425 , A2513200025 , A2513200325 , A2513200425 Applications For Mercedes R Class 06-11 Platform W251 Features - 2 Year Warranty - Condition: Brand New - Placement on Vehicle: rear left or right side - Quantity: 1 piece - OEM Product: Easy to install - Test more than 5,000,000 times: Durable and Safe - 24 hours air tightness test ≤ 0.02MPa: Air Tightness Guarantee - Temperature Range ≥ -40℃/ ≤ 70℃: Premium Natural Rubber Material Important Notice - Professional installation is highly recommended. - For any needs please contact us via eBay message