Description of productsTechnical Information Classes of Internal Threads and Classes of Taps Pitch Dia. tolerance zone of 5H=100μm : (Tolerance 20μm) class 3 class 2 class 1 Internal thread : Tap : Pitch Dia. tolerance zone Pitch Dia. tolerance of 5H Basic Pitch Dia. 3. Comparison of pitch diameter tolerance zone for the classes of internal thread and tap. Following graph shows : In metric coarse threads (1) Tap limit classes of YAMAWA P class. (2) Pitch diameter tolerance zone of 2nd class (Tap) of JIS Appendix (old JIS) and that of class 2 (Tap) <class 1 for M1.4 and smaller>of the main book of JIS (current JIS) . (3) Pitch diameter tolerance zone of old JIS 2nd class (Internal thread) and that of JIS 6Hclass (Internal thread) <5H class for M1.4 and smaller> (4) Pitch diameter tolerance zone of standard classes of YAMAWA P class. P class Pitch Basic Pitch Dia. Sizes HT,SP,PO JIS class 2 class 1 HT,SP,PO JIS class 2 class 1 HT,SP,PO JIS class 2 class 1 HT,SP,PO JIS class 2 class 1 SP HT,PO JIS class 2 P class class 2 Pitch diameter tolerance zone of recommended class for YAMAWA P class SP HT,PO JIS class 2 class 2 Standard class of YAMAWA Spiral Fluted Tap HT,SP PO JIS class 2 class 2 Standard class of YAMAWA Spiral Pointed Tap HT SP HT,PO JIS class 2 Standard class of YAMAWA Spiral Hand Tap class 2 class Pitch diameter tolerance zone of tap in the main book of SP HT,PO JIS class 2 JIS (current JIS). class 2 Class 1 for M1.4 and smaller, class 2 for M1.6 and larger SP HT,POclass 2 JIS class 2 Pitch diameter tolerance zone of internal threads in oldJIS class 2. SP HT,PO JIS class 2 Pitch diameter tolerance zone of internal thread in current class 2 JIS (ISO)Class 5H for M1.4 and smaller, class 6H for M1.6 and larger Technical-14