Which panels hold what temperature? The “series” and color codes are: Series 4 (blue tab) maintains a refrigerated temperature. Series 20M (black tab) maintains a frozen temperature. Series 22 (tan tab) maintains a room temperature. Post navigationPrevious post: When are panels ready for use? Next post: How long does it take to prep the Cool Cube™ for pack-out? Comment on this FAQ Cancel replyYou must be logged in to post a comment.