This original Nintendo brand product is still the best quality RF you can get. It has a screw-on type coax connector to the back of the TV for best signal quality.
Our new exact replica RF switch (made by a third party) is also a screw-on coax connector for a great signal quality, and is less expensive.
Make sure the RF Channel switch on the back of your console is set to the same channel (either 3 or 4) as your TV.