I posted this in another thread..

Roadster Antenna base gasket ???
This is what I bought.

Gasket Price: US $0.88
Roof Antenna Base OEM Gasket Seal For VW Mk4 Golf Jetta Passat Bora EP | eBay

16 inch antenna Price:US $1.86 + 0.15 Shipping
16" Car Vehicle Screw-in Radio AM/FM Roof Antenna Aerial Mast Replacement P9R7 | eBay


These are the parts I was looking for. I don't need to get the base and throw it away.