A nanotainer is the proprietary name for a tiny vial, less than half an inch tall, intended to hold a few drops of blood as part of the self-described “disruptive” blood testing technology invented by Theranos.

Theranos claimed that its proprietary technology allows it to run as many as 200 blood tests on just a couple of drops of blood, drawn via finger prick instead of a needle, that are contained in the Nanotainer.

However, when the federal Food and Drug Administration conducted unannounced inspections of Theranos facilities in August and September 2015, it reported that the nanotainer is a Class II Medical Device, for which manufacturers must use special labels, meet performance standards, and conduct post-market surveillance. FDA noted that Theranos was using the device without its clearance or approval.

Theranos argued that the nanotainer is a Class I device, for which there are no regulatory requirements However, the FDA documented a number of complaints from its inspections, including that a the Nanotainer had a design evaluation that didn’t ensure the device “conforms to defined user needs and intended uses.” Additionally, the nanotainer “was not validated under actual or simulated use conditions,” and the risk analysis for the device hasn’t been adequately documented. FDA also said there were inadequate procedures for logging customer complaints, and that complaints that Theranos’ technology didn’t work weren’t reviewed or investigated.

Theranos had become involved in legal proceedings in 2014 following objections filed to Theranos’ trademark application by Becton Dickinson, which holds a trademark for the name “Microtainer.”

Theranos responded by filing papers asking that the U.S. District Court for the Northern District of California rule that “nanotainer” does not infringe the “microtainer” trademark used by Becton Dickinson. The parties arbitrated and settled their dispute on Sept. 28, 2015 with apparently no money changing hands.

However, in October 2015, Theranos founder Elizabeth Holmes announced that the company was no longer using the nanotainer except for one FDA-cleared test, HSV-1, for which it earned FDA clearance in July. For more than 240 other blood tests, she said, Theranos was performing traditional venipunctures with test tubes and standard analysis technology.

As of late 2015, Theranos had released no data or peer-reviewed studies to prove its claims for the nanotainer or its blood analysis technology. After becoming the target of a major expose by the Wall Street Journal,, CMS sanctions and numerous lawsuits in 2016, the company announced that it was leaving the clinical lab business to focus on device development instead.