If you need to mount an inconspicuous boundary microphone into a table up to 3" thick, consider the Astatic 220VP Microphone from CAD. Styled in black, this mic is designed for speech pickup in governmental, institutional, religious, and similar scenarios.
The 220VP is a compact, button-style condenser mic with a continuously variable polar pattern. After the mic is installed into surfaces measuring up to 3" thick, the microphone will operate free from interference from cell phones, two-way communication, and other RF interference.
You can precisely tailor the polar pattern of this mic for the best performance, depending upon the application or environment. The mic offers a built-in 80 Hz high-pass filter to remove unwanted low-frequency information to bolster intelligibility. The mic has a threaded, all-metal construction to mount easily into hard surfaces. In fact, when you mount the mic into a hard surface, such as a wooden table, the microphone takes advantage of acoustical effects to improve the signal to noise ratio.
The 220VP terminates in a 3-pin XLR connection recessed into the mic itself. is terminated with a standard 3-pin XLRM-type connector recessed in the body of the microphone.