One Codex Reformat Tubes barcodes and human readable Barcode IDs are etched on the side of each tube. The Barcode ID is formatted as a 10 digit alphanumeric code. These tubes also have a matching 2D barcode on the bottom of the tube.
Standard OMNIgene•GUT collection device barcodes can be found on the label on the side of the tube. The Barcode ID is formatted as a 14 digit numeric code. DNA Genotek does sell custom barcoded tubes, so this may not apply if you have custom barcoded tubes.