The UPD high performance M275, M277, M279 M137, V12 billet 4 piece replacement idler set will replace your stock plastic double idler pulley assemble and tensioner pulley with a high quality CNC billet aluminum machined performance pulley set. High quality Nachi bearings are used and only double bearings seals are used to protect bearings from heat and dirt. All our billet performance idlers have a ultra hard anodized coating and custom billet bearing shields for looks and dirt protection.Our leading AMG Mercedes idler designs have been on the market since 2008 and installed on thousands of AMG cars! 
Note: v12 engine pic is of 3 of the 4 idlers to show what stock and Billet differences are and one bearing cap is shown to also show what parts look like without billet bearing shields. 

•  CNC billet aluminum with hard anodized coating 
•  ZZ rated high speed Nachi bearings 
•  Smooth and quiet running 
•  Easy install 
•  Made in USA and highest quality available 

Replace your idlers with UPD`s performance idler set today, as the stock AMG plastic idler`s, with rubber bearing seals,are known to fail from the high heat and dirty conditions under the hood.  Replaces 1132020419, A1132020419, A 113 202 04 19
Fits all Mercedes and AMG V12 biturbo and N/A engines M137, M275, M277, M279. Fits all SL65, CL65, S65, G65 CLK 65 Black series and Naturally aspirated V12 Mercedes engines 2001-2021.  Maybach 57 and 2 S trim, Maybach S 650 , Maybach G 650