Two 16 MHz Ceramic Resonators
This is for two resonators. This is a Breadboard compatible 16 MHz Ceramic Resonator. These are used with many micro-controllers like the ATMEGA328P to give it an external clock. The center pin is meant to connect to your ground bus and the two outer pin connect tor your clock or 'XTAL' pins. Most crystal oscillators require external decoupling capacitors, but these resonators do not normally require external decoupling capacitors. Please ensure it is as close to your MCU device as you can make it though.