X-Nape is 2X more stable than conventional systems and is the preferred system for monocular NVGs (PVS-14, PVS-18). H-Nape is 3X more stable than conventional systems and includes a 5th adjustment point for those times you need a very tight fit, this is the preferred system for binocular NVGs (PVS-15, PVS-6, PVS-9) or Jumpmaster duties that require outside air safety checks. Mounting hardware included. Gas Mask Extender does not work with LED (left eye dominant) version. Ops-Core ACH Head-Loc™ Retention System H-Nape, 2011 Version Ops-Core ACH Head-Loc™ Retention System X-Nape, 2011 Version Ops-Core CBRN Mask Extender 2011 Version Clearance Ops-Core ACH Head-Loc™ Retention System H-Nape 2007 Version Ops-Core Ballistic Mounting Hardware (4 pcs) Items marked "(R)" No Export, No Paypal, NO EXCEPTIONS OPT Facebook Page Item Availability/ Store Hours: Add the item to your shopping cart and the next screen will show if it's in stock. optactical@yahoo.com or 1-919-818-3649; Monday-Friday 7:30am-3:30pm Eastern Standard Time (EST) Payment: Visa, Mastercard, Diner's Club, Paypal and Impac Card Discounts: Orders shipping to North Carolina addresses use coupon code "NCRES" for tax-free discount. Use of this code for any non-NC-taxed orders will be deleted Shipping: UPS Next Day, Second Day, and Three Day orders must be received by 12 PM EST $12 Priority Mail to APO/ AE (Europe / CENTCOM) International, see the left margin tab marked "SHIPPING" Veteran-Owned Small Business, accepting Government Contracts CAGE: 5MU18 / DUNS: 361562593