This is an Antenna Adapter commonly found on many Dodge and Jeep vehicles. 
The CR20 is the reverse antenna adapter, to adapt from a motorola end back into the factory antenna style to plug into the factory stereo.
You would use this product when installing a FM modulator while using the factory headunit. 

Please visit www.MetraOnline.com to use their fit guide to determine if this is the correct antenna adapter for your vehicle. Thank you.