1) According to materials: iron sleeve steel sleeve plastic sleeve nylon sleeve
2) According to Luo Ya:
Fine teeth: Rib diameter DN 34.5, pitch 1.5 teeth, usually used for C-type guns (C-type also has coarse teeth);
Coarse teeth: Rib diameter DN36, pitch 2.0 teeth, usually for B-type guns
Other pitches are 5/8 teeth.
Can be processed according to drawings.