Suggestion guys.

Try to buy a Green dot one as it is easier
to see in Daylight. AND if possible, get one
which the dot can be changed in size.

Like one of the previous posters said,
I am also colourblind Red / Green.

Also, the military is going to green and having
used MG's like H&K's etc with Red,
I can understand why they are going to Green.

Same as lasers - always try to get a green one.