Developed around 1915, the Haeussler pistol is a straight blowback semi-automatic using a proprietary cartridge and a hinged dust cover assembly for easy field stripping and cleaning. Mechanically, the pistol shows a strong resemblance to the work of Hugo Borchardt and Georg Luger, especially in the sear striker assembly, the overall shape of the frame and the grip angle. Blade front and notch rear sights, with a tapered barrel, "crown/crown/U" proofs on the barrel, receiver and breechblock, "PATENT HAEUSSLER/WAFFENWERKE/ENGELBRECHT & WOLFF" on the right side of the frame, straw finished trigger and safety, and finely contoured checkered grips. Matching full and partial numbers are present on multiple parts, including the blued magazine.