This is a side cocking upper receiver that fits your M11/9mm. This comes with steel military spec picatinny rail and the rail is available in two different heights: 1/2″ (standard) or 1/4″. There may be a slight delay on the shipment of this product due to the custom picatinny rail height. The rail height shown is 1/4″ and there is an additional $25 fee due to the customization of the rail height. This product is just the upper with no bolt or barrel. This item is a special order item, please allow at least two weeks for shipping.