In a wedge braking system, the brake chamber directly faces the brake drum. Compared with S-cam drum brakes, wedge brakes lack the exposed linkage of the pushrod, clevis pin and external slack adjuster. (Most wedge brakes have internal automatic adjusters.) Today, most commercial vehicles have disc brakes or S-cam drum brakes. However, wedge brakes are still favored for some military and other applications for which the lack of exposed linkage is advantageous on rough, corrosive, or dangerous ground.