tan·dem 
/ˈtændəm/ noun
plural tan·dems /ˈtændəm/ noun [count] 1 : tandem bicycle 2 chiefly US : a group of two people or things that work together or are associated with each other
▪ The team has a tandem of talented guards. ▪ He and his partner make/form quite a tandem. [=duo]
▪ The team has a tandem of talented guards. ▪ He and his partner make/form quite a tandem. [=duo]
in tandem
of two people, groups, or things : working or happening together or at the same time
▪ They moved in tandem. ▪ The two products can be used alone or in tandem. ▪ They're working in tandem with scientists from England to find a cure.
▪ They moved in tandem. ▪ The two products can be used alone or in tandem. ▪ They're working in tandem with scientists from England to find a cure.
