This is the ATMEGA328P-PU used with the Arduino UNO. This comes with your choice of firmware and a socket.

We can load the 16 MHz firmware that makes it compatible with the Arduino IDE as an Arduino UNO or the 8 MHz firmware that makes it compatible with the Lilypad Arduino. All ATMEGA328Ps are flashed, tested, mounted on anti-static foam, and placed in an anti-static bag. Each ATMEGA328P comes with a socket to mount it on your perf-board project.