Question: what does unef thread mean?
Answer: UNEF: Is the symbol for United extra fine pitch threads. UNS: Is the symbol for Unified special threads. For instance, if the nominal diameter is a: 1/4" UNC, the number of screw threads is 20 (Coarse thread) (Pitch: 25.4mm ÷ 20 threads per inch (TPI) = 1,270mm)