These fit the Magpul MBUS Gen 2 polymer sights and any sight that accepts a standard A2 type post. The MBUS PRO and the MBUS Gen 3 each have their own unique post design and we have posts available that are made specifically for those. But the chevron format doesn't work with the MBUS PRO and MBUS Gen 3 sights.
No this will not fit on the mbus 3 not the mbus pro. Just the mbus one and two due to the width of the screw. The mbus 3 requires a slightly thinner screw and this will be too big