The only 100% waterproof PLUG and PLAY installation plug for sale. Co-Molded nylon & elastomer plug naturally seals / water proofs antenna cutout. Keeps out water and debris with no use of any sealant. Fits perfectly snug into your OEM BMW antenna cutout with no modification. Locking tabs snap into cutout with fingertip pressure. Fits EVERY year E36 models provided OEM cutout has not been modified and measures .85 inches in diameter.