EMERSON MICH Helmet Retention System H-Nape. The MICH Helmet Retention System H-Nape was developed to improve safety, comfort and stability of chinstraps used in MICH/ACH ballistic helmets. Every component, down to each stitch pattern, was designed specifically for this purpose, giving the ACH greater utility than ever before. Custom adjustment tabs allow the helmet to be adjusted while wearing it, without any hanging loose ends. Simplified strap geometry makes the system 3X more stable than existing chinstraps.