For inside and outside measurement in metric or English units. Ideal for learning precision measurement techniques by using the vernier principle. Has metric scale to 12.5cm in 1 mm steps and the 10 part vernier reads to 0.1mm. English scale is graduated to 5in in 1/16in divisions and the 8 part vernier reads to 1/128in. Features a locking pin to secure readings and knurled thumbwheel permits fast, easy measuring. Beveled cross horns are useful for internal measurements. Made of plated steel and packed in a plastic case.