A sight mechanism for firearms such as pistols, rifles and the like. The sight mechanism includes a sight member that has a rear sight that is vertically adjusted. The sight member can be mounted on a vertically moveable member that has a fixing member that sets the vertical position of the sight member. The vertically moveable member may, without limitation, be a pivoting member. The sight mechanism includes magnets that bias the vertical member against the fixing member so that the magnets maintain the sight at the vertical position defined by the fixing member.