Helps drivers improve the accuracy of their log book calculations, reducing the chance of excess hours on duty, violations, and fines Reflects current HOS Rule for property carrying drivers Hours of service ruler runs along top edge for easier use Tire-tread depth gauge printed on back side Made of yellow durabrite flexible plastic Measures 2" x 7-1/4" (for 5-1/2" x 8-1/2" or 8-1/4" x 8-1/2" log books, KellerScan logs and all small log summary envelopes)