That's right Astronomy fans, 20% off of all OSI products!
Excludes items already on sale.
Sale begins May 5th at 00:01 PST and ends May 8th at 23:59 PST.
AT CHECKOUT, ENTER COUPON CODE:
May 5th: National Astronaut Day
May 6: National Space Day
May 7: International Astronomy Day
May 8: Mother's Day