1951 American Chemical Society Plate Block of 4 3c Postage Stamps - MNH, OG - Sc# 1002
These are real USPS postage stamps that are accepted by the USA Postal Service as payment for mail posted in the USA however the total rates on the stamps posted must equal or exceed the current appropriate postal mailing rate or extra postage must be paid.
The stamp set shown in the picture is a stock photo and is likely not a picture of the exact stamp set you will receive in that it may differ in plate number and/or orientation. However the item you will receive will be similar including having a plate number (if one is present in the photos) and the same number of stamps. Stamps titled as MNH, OG will have no significant creases or unnatural gum disturbances unless otherwise noted.