The Walther PPK/S (or "Polizeipistole Kriminalmodell") is Sterling Archer's preferred and primary sidearm. First introduced in 1931, this weapon is famous as the weapon of choice for James Bond, the inspiration for Archer himself. Archer's PPK/S is chambered for the .32 ACP cartridge with a magazine capacity of 7 rounds plus one in the chamber, and is preferred over others because its compact design doesn't ruin the lines of his bespoke suit.
Archer is a crack shot with the Walther, frequently using it to shoot people he doesn't like, those who are annoying him, and occasionally himself. He has also been known to shoot people who enter rooms he is in after he has warned them to stay out ("Job Offer").