GPS vhf antenna, looking for plastic cover on sma connector

[Beardawgs]

I have a Garmin Magnetic Mount antenna for the GPS and the connector ripped off. I'm trying to find the black plastic piece that slips over the hex nut part of the male sma connector. It would have to be put on the cable before crimping the connector. I also want to shorten the cable on my new 49" whip to get rid of the fme to sma connector to make it easier to screw onto the GPS, and have less cable on the 4wheeler. What is that piece called and where can I find it? Thanks!