I have them for my boat, they came from the original owner's so I am unsure fo the price but $75 seems about right. They are not used when running, it will block the air intake in the back and starve the engine for air, they are used for storage to keep the engines out of the elements, my cowlings look brand new and shine. I put them on unless I will be down the next day, otherwise I use them to keep them in top shape, I know many cowlings lose their shine and color from sitting outside year after year so this is a ncie touch, plus they look nice on the engines.