HELMET ASSEMBLY12-8. The ACH has a unique, fully adjustable pad suspension system. The only authorized suspension pads are those issued or purchased through official U.S. Army supply systems. All suspension pads will be secured to the helmet shell by hook disks. There are two sizes of suspension pads, size 6 which are three-quarter inch and size 8 which are one-inch thick. All seven suspension pads will be the same size, do not mix and match suspension pad sizes or manufacturers. Serviceable suspension pads will be free of any rips or tears that expose the foam padding inside the shell. All seven pads are worn with the helmet. (See figure 12-2.) 12-9. The placement of the oval pads must cover the four bolt ends of the four adjustable buckles in the helmet shell. The oval pads must be placed vertically inside the helmet shell to maximize impact protection. The crown pad may not be replaced by two oval pads. One trapezoid pad will be positioned at the front of the helmet shell and one at the rear. The front trapezoid pad will be flush with the outer rim of the helmet shell. The rear trapezoid pad can be flush with the outer rim or extend up to a half inch past the outer rim for maximum protection. (See figure 12-3.)