These hose adapters allow you to install a Sanden SD508 / SD709 / SD7H15 / SD5H14 compressor on an M20 engine while retaining all factory A/C lines. This makes the Sanden a drop-in replacement (with appropriate bracket and belt). These require no modification to factory oil cooler lines or fuel cooler lines. Reference this post for nuanced detail. Fitment of these adapter hoses (manifold hoses) has been confirmed with the following compressors: Sanden 4272 SD7H15 — requires 90° rotation Sanden 6630 SD5H14 — no rotation required E30s equipped with M20 engines originally came with Bosch, Seiko, or Denso compressors. These adapter hoses are compatible only with vehicles originally equipped with a Denso 10P15E compressor. If your E30 was originally fitted with a Bosch or Seiko compressor, you will need to replace the low-pressure (suction) line with an OEM Denso line for proper fitment. Price: $230 + shipping ($10 US/Canada, $30 international).