I wear a cheap plastic style that are orange that go around your neck and have replaceable sponge ear plugs. I get asked at Sturgis by someone every year as to where you get them. They are an industrial type that employers provide for their employees. The nice thing is that you can wear them around your neck when you stop, so they are always with you when they are needed.
You can still hear the stereo when wearing them and talk back and forth with your passenger. I wish that I knew the manufacturer, but I don't see a name on the packaging or the product.