The heart of the GL45 connection system is a GL45 polypropylene cap with GL18 threaded ports

Modular accessories include polypropylene tube connection caps,solid polybutylene terepthalate (PBT) caps, PBT pressure equalization caps and PTFE cap inserts to accomodate various sizes of tubing. A typical application is the safe transfer of liquid media within a closed and sterile system for which you'd need one two-pack GL45 cap, two 89214-900 equalization caps, and some combination of solid caps and tubing connections with inserts.