One of the most prolific issues of stamps ever released. There are numerous dates, and printers, and microprinting on these stamps that all have their own variety listings. None are considered to have any extra value, but specialists can have a field day trying to collect all of the different specimens that seemingly look alike on the surface. Here's a link to a previous post on this site that shared some discussion on it:
https://goscf.com/t/331Even though the above link relates to 2007 issues, the respective 2009 dated issues are subcategorized as 4125d (11.25 x 10.75 on 2 or 3 sides with bell 16mm wide and large microprinting); 4126d (same as 4125d except for small microprinting and 2009 printed in copper); 4127i (same as 4125d except for medium microprinting, bell 15mm wide, and date printed in copper); and 4128b (serpentine die-cut 8 on 2, 3 or 4 sides).