They are a special spray bottle contraption that sprays a light mist of oil. You fill them with your oil of choice, and they spray somewhat like Pam. You cant just use any old spray bottle though, I am told, as they will clog.
Here is a description of one from Amazon. I did a search on "cooking oil sprayers"
For spreading olive oil evenly on bruschetta, focaccia, and grilled or roasted vegetables, and for spraying muffin and cake pans with vegetable oil, this dispenser is a nifty tool. A plastic cap underneath the sprayer's top twists off so the sprayer can be half-filled (1/3 cup) with oil. Inside the top is a plastic tube that fits over the spray nozzle. Push the top up and down to pump air pressure into the canister. Then spray for 10 seconds and pump up again. It's simple, ingenious, and practical. With its cap on, the sprayer stands just 7-5/8 inches high, so it tucks away easily on any countertop. Made of satin-finish stainless steel with a black-band accent, it's sleek as well as utilitarian
Reviews on them are mixed. The one my friend had worked terrific. | 
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