Often preferred in laboratories due to their adherence to UN/DOT standards, these “tight head” containers with a Rieke® 70mm threaded cap are supplied in two different thread variants: a 6TPI and an 8TPI (where TPI stands for “threads per inch”). In some areas, local regulations allow these containers to be shipped directly from the lab to incineration facilities - which can be a significant benefit of using a DOT-type container. Telling the difference between a 6TPI and an 8TPI thread can be tricky, but many Rieke® caps include the TPI number embossed along the rim of the cap. If not, verify with your container supplier or request a sample cap to test fitment.