Insert the tube with the saliva sample in the box to send it back, if you also have a biohazard envelope, you can put it in the envelope and this in turn into the box.

If you have more than one sample you should send all together.

Once the sample is inside the box, you just must introduce it in the envelope for shipping, as described in the illustration (it has UN3373 written on it). Close the shipping envelope as tight as possible to the box, so that it is not loose inside the envelope, and thus is more protected.