Jiufan New Black Tactical Rifle Back Up Front And Rear Physical Aiming Sight Set With Box Both front and rear sight bolt firmly to the 20mm weaver rail. Great back up sights for any gun with a continuous flat top rail. Spring loaded flip-up system, release lever can be reached on left, right and top position. Impact resistant polymer construction provides light weight and resists operational abus This back up sight fits all 20mm rail euipped weapons