I have all 3 modifications of the baby I frame. 1) 4 digit SN moon front sight, 2) 5 digit SN smooth ramp front sight, then 3) the serrated ramp front sight. All 5 screw pre-model 36 with the early flat latch. Sold another 4 digit SN moon sight as someone decided to nickel plate an originally blued one. Has taken me a while to get this far into them.