Metric size Inch size 23 04 06 08 10 12 Thread type 01 03 05 07 09 11 13 Nil Metric thread (M5) Unified thread (10-32 UNF) R NPT 1/8" 5/32" 3/16" 1/4" 5/16" 3/8" 1/2" 3.2 4 6 8 10 12 Port size M5 U10/32 01 02 03 04 M5 x 0.8 10-32 UNF 1/8 1/4 3/8 1/2 N Use 1/8" tube.