Flexible modular GL 45 connection cap system that accepts four different rigid or semi-rigid tubing diameters (1.6 mm; 3.0 mm; 3.2 mm and 6.0 mm). The caps are available with 2 or 3 GL 14 threaded ports. The different sized inserts form a tight seal around the pass-through tubing. Sterile pressure equalisation is possible through use of 0.2 μm syringe filter. Unused ports can be sealed off with a red GL 14 screw cap.