Currently we are not offering a $20 coupon that is specific to online orders. We recently had a $20 member bonus card event where members could receive a $20 bonus card when they spent $100 between July 9 - 29. The $20 member bonus card is redeemable now until August 12, in stores and online. That may be the coupon that you are inquiring about.
If you're not an REI member yet, we are currently having an incredible new member bonus card event! An REI lifetime membership is a one-time purchase of $20 and if you spend $100 from now until August 29, you can receive a $20 bonus card! More details on the new member bonus card here. For membership information, take a look at this link. You could also ask the community what they like about the REI membership and we're sure you'll get some awesome answers there too!
While we are here, there's another great place to take a look at the current coupons and discounts that we are offering. Check that out here!
Thanks again for your question, we hope this helps!