I need to replace the stock front sight pin with a night sight pin. Are these 100% 'drop-in' replacements??

Rifle: RRA M4 Tactical Entry LE

Who makes/sell them?

How much I am looking at?

Also, will there be any problems with having a night sight front sight pin, later when I add a EOtech or Aimpoint?

Thanks for any and all info.

Yes the Trijicon is a drop in part(although as with all things the ever present possibility of tolerance stack occurs). I put the front/rear set in my RRA M4 entry gun and afterwards thought I should have only put in the front post until I got my Aimpoint mounted.Now at night I can use the 2 rear indicators with the red dot between them for a very precise aiming point. With the target illuminated with a tac light this all combined provides a very positive aiming point at a modest cost. I got mine from ADCO and I think the set was like $75 and I've seen the front posts alone advertised for +/- $45. The posts are slightly wider than the stock post but this should not be an issue on this type of weapon.

I was originally looking at the front/rear night sight set. However, I eventually wanted to add an optic to my rifle, EOtech or Aimpoint. I was unsure if I would be able to mount an optic and use the current RRA M4 'tactical mount-top' with the stock rear sight setup. I thought I may have to buy a new mount and new rear sight when adding an optic so I would be able to use the iron sights with the optic.

For $75, I may as well buy the set for now. What insert/illumination does the rear sights have? I was assuming it may be a tritium shaped ring, but have seem some which are just dots around the aperature.

Has 2 dots 1@3:00 1@9:00. Mount an Aimpoint using the standard Aimpoint ring for perfect cowitness at an affordable price in a finish that matches your upper and sight.Then you will have full time irons with tritium illumination and electronic sight all cowitnessing and requiring no folding,springing,deploying or other hoop jumping to use your sights clean and simple.If the electronics fail you are already on your sights night or day.Additionally you lose your rear elevation adjustment with some of the more popular BUIS(which sucks). The little cavity on the right side of your tac-handle holds an Aimpoint battery. Eotech requires different mounts all together has a greatly diminished battery life and is not significantly less expensive. The only advantage that I can perceive with the Eotech is availability of a 1moa dot but on a weapon of this type I feel this is a feature of minimal value.YMMV