Boston Leather Mark Iv Chemical Holder . Flap Cover Holds Mark Iv Units. (w/ Velcro Closure) Holds Mark Iv Units Basketweave Black Package Contents: Boston Leather Mkiv Holder W/flap Basketweave Black The Boston Leather Mkiv Holder W/flap Basketweave Black is a quality addition to the Boston Leather lineup. For more great deals on Survival Gear by Boston Leather please browse our Boston Leather Survival Gear page.