UMI poly engine mount kits are a great combination of high performance and comfort for your SBC engine needs. Featuring tough 3/16 construction, modern poly formulations and a racing pedigree, trust UMI's poly engine mounts to deliver the results you demand for your ride. Bolt In or Welded In: Bolt In. WARNING : This product can expose you to chemicals including Styrene, which is known to the State of California to cause cancer.