@CaseyShannon thank you for reaching out!
Sounds like you got your hands on a real gem with your sleeping pad find! We appreciate you considering a sustainable alternative by choosing to re-use gear and keeping it out of landfills!
While it does not appear that Therm-a-rest was using R-value ratings at that time, similar sleeping pads come in at an R-value of the mid three range. However, we recommend that you reach out to Therm-a-rest directly for more insight into their R-value rating process for older sleeping pads; we just don’t have visibility and would want them to have the opportunity to answer your question accurately. You can reach out to Cascade Designs (Therm-a-rest parent company) directly at 1-800-531-9531 or by e-mail consumer@cascadedesigns.com
Hope this helps!
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