High carbon steel blade for maximum blade extension. Long-lasting stainless steel spring for smooth operation. Reads to 1/16"" graduations. Sliding hook for inside and outside measurements. Designed with sliding thumb lock and quick auto return high-impact ABS case. ⚠ WARNING: This product can expose you to DEHP, which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.