It are ideal for laboratories requiring secure, leak-resistant sealing for various sample containers. These high-quality caps feature a phenolic resin construction with a PTFE liner insert for enhanced chemical resistance and an airtight seal. The 13-425 threaded design ensures compatibility with most standard laboratory vials, and the pack of 200 provides ample supply for high-volume laboratory use. These caps are commonly used in chemical, pharmaceutical, and biological research to prevent contamination and maintain sample integrity.