Every circular hole labeled with corresponding size value, intuitive and easy to operate without complicated reading steps for new moms to master quickly. Smooth polished edge design removes sharp burrs, avoid scratch discomfort when attaching to breast skin during repeated size checking. Stable hard plastic structure resists slight bending and deformation, maintain clear size printing and intact circular holes after long-term repeated use. Wide applicable scenes cover pre-pump accessory matching, postpartum nipple size confirmation, maternity hospital nursing guidance and daily breastfeeding preparation. Individual OPP bag separate packaging effectively prevent dust and surface scratch during storage and transportation, keep measuring card clean before use.