This part of GB/T 1149 specifies the basic dimensional characteristics of the steel belt combined oil ring, and does not specify a complete product description (because the piston ring manufacturer is different, the structure of the lining ring is also different, and the specific design details are to be shared between the manufacturer and the customer. Agreed). This part is applicable to steel belt combination oil rings for road vehicles with cylinder diameter from 40 mm to 125 mm and for reciprocating internal combustion engines for other purposes. Compressor piston rings working under similar conditions can also be used as a reference.