Colt 38 special magazine follower

Have two types of followers on some mags i bought the other day.
Are the raised follower aftermarket.

I’ve seen them in magazines both with and without the Colt base plate. Not sure if it was generational.
Jon

That is known as the "Kruger Modification". The follower modification is credited to Illinois State Champion shooter Ellwood Kruger who silver soldered a 5/32" piece of bar stock to the centre fold of the follower to make the last round strip cleanly from the magazine. I've seen dozens of Colt .38 Mid Range magazines with this and in my stash I have 2 of them. This modification is covered in Bill Jenkins book U.S. Military Match and Marksmanship Semi-Auto pistols.