Check the listing for details. National FB-7 Plug-in Coil Set C, 4.0 to 7.3 MHz, Nice. Color: Black, Condition: Used, Made in United States. Listed at 49.99 USD. You are bidding on a coil set for a National FB-7 receiver. This is coil set C, which is for 4.0-7.3 MHz. They are in good usable condition, one for detector and the other for oscillator. I notice that the oscillator coil has an adjustment screw at the top. They are in good condition and complete, but I do not have a way to test them. They have the unique 6-pin base configuration that National used. I believe these are the same as SW-3 coils without the top handle. Not counting the pins and handle they are roughly 2 3/4 inches tall, and 1 3/4 inches in diameter. They should be needed. Shipping weight is 1.25 pounds. Please see my other auctions for more interesting radio and audio items, and tubes.