A -55^o Centre Gauge
B -60^o Centre Gauge

Combined threading tool gauge for ACME 14½^o and angular threads 47½^o 55^o, 60^o

The universal grinding gauge combines twist drill grinding gauge, center gauge, hexagon and right angle, 55^o and 60^o 

For twist drills with an acute angel of 118^o up to 50 mm and 2in diameter.