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 2006-2010 Platform W251 Features - 2 Year Warranty - Condition: Brand New - Placement on Vehicle: rear left & right side - Quantity: 2 pieces Advantages 1. Product Certification: ISO9001:2015 2. Stress Test Over 3,000,000 Times: Durable and Safe 3. Burst Pressure ≥ 2.0MPa: High Compressive Strength and Less Noise 4. 24 Hours Air Tightness Test ≤ 0.02MPa: 100% Air Tightness Guarantee 5. Temperature Range ≥ -40℃/ ≤ 70℃: Premium Natural Rubber Material Important Notice - Professional installation is highly recommended; Instruction Included. - For any needs please contact us via eBay message