The importance of the stud mount cannot be overstated! The antenna stud mount acts as a bridge between the antenna and the coaxial feed line. Accordingly, it needs to allow for efficient transfer of your signals to and from the transceiver. If the stud mount doesn't perform that task efficiently, you end up with unneeded loss. And if that isn't enough, the stud mount must be strong enough to withstand the stress from an antenna subject to severe wind load and vibration.
Firestik stud mounts have become the industry standard. This wasn't by accident; it's because users learned to appreciate their outstanding design and quality material. Instead of inexpensive aluminum, Firestik uses chrome-plated machine brass. Instead of 9/16" (14mm) hex stock, they use 5/8" (16mm) stock. Instead of ABS or inferior plastic insulators, they use nylon. Instead of cadium-plated hardware, they use stainless steel. And their heavy-duty 3/8" center shanks can mean the difference between trouble-free use and lost antennas. Some businesses have copied the look of the Firestik antenna studs, but those "low-cost targeted" parts have a tendency to come apart -- it's buyer beware! You might save a dollar, but you could also lose a $25+ antenna as your "reward."
This K-4A stud mount has been praised by communications professionals for 20 years. You can actually pay more for a stud mount but you certainly will not get more than what the K-4A offers. The K-4A should be used whenever a PL-259 terminated coax cable is to be used (K-8A, K-9A, R-8A, R-9A). Like the K-4, this stud is designed for 1/2" (13mm) holes. In a typical installation, antennas with 0.680" (15mm) of exposed threads can be used without the fear of bottoming out before proper tightening is accomplished.