UMB-1 Universal Mattebox (Clamp On) comes standard with two rotating 4x5.65 filter stages (with an optional third stage available), individual tray catchers, folding French flag, 143mm native diameter opening, NATO standard accessory rails on left, right, and top for attaching accessories, and a complete set of clamp on reduction rings. The UMB-1 is designed to be user upgradable and quick to transition from clamp on, to swing away, to ultralight when using a stabilizer. Upgradable to Swing Away or Clamp On versions when needed.