Patented roller release mechanism extends the life of the M series for hundreds of thousands of cycles. Made in the USA and ships in an American made plastic box. Patented lock ring is easy to use. Wide usable scale from 20-100 Lb. Ft. with 3% accuracy and flex head. All steel construction for increased durability Engineered, precision bearing surfaces extend the calibration life of the M line to as many as 60,000 cycles or more and ensures the most reliable performance possible. Meets or exceeds ASNI/ASME B107.14M, GGG-W-686C, GGG-W-2843 and ISO6789.