A COVID-19 Rapid Diagnostic Test, a simple testing device similar to a [[pregnancy test]]. 

They're a lateral flow test used to determine either COVID-19 antigens for a current infection or COVID-19 antibodies for having had a past infection.  The antigen test features marks for C and T, where a single line on the C indicates negative for infection, while a line at both C and T indicates a positive for infection.  The antibody test features the marks C, IgG, and IgM or C, G, and M.  Having a line at the IgG or IgM mark indicates the presence of antibodies and having had a past infection.

h4. External links

* "Wikipedia: COVID-19 testing":[https://en.wikipedia.org/wiki/COVID-19]
* "Wikipedia: COVID-19 rapid antigen test":[https://en.wikipedia.org/wiki/COVID-19_rapid_antigen_test]
* "Wikipedia: Lateral flow test":[https://en.wikipedia.org/wiki/Lateral_flow_test]
covid-19 test