ClikSeal containers are leak-resistant and ideal for pneumatic tube systems. The audible "click" you hear when you tighten the lid assures you that the cap is seals and ready for transport. All ClikSeal containers have a blue screw-on cap designed to enable stacking of multiple containers. Item has a sterility-seal and patient I.D. label affixed to the container with lines for date, number, name, and doctor. For Pneumatic Tube Systems- Specimen Container, 4 oz, Label & Gray Lid, Polybag, 100/cs (60 cs/plt)