Abstract: The present disclosure relates to a throwaway device to check and measure respiratory flow rates. The device 100 incorporates a first deflector 104, a blade 108 and a second deflector 106 enclosed inside a housing 102. The first deflector 104 configured at a front end of the housing 102 to facilitate inflow of air inside the housing 102. The second deflector 106 is configured at the rear end of the housing 102 to facilitate outflow of air. The blade 108 is having two conical ends 110 at two opposite edges. The blade 108 positioned between the first deflector 104 and the second deflector 106 which is configured to rotate about a rotational axis A-A?. A mouth piece 112 is removable attached at the front end of the housing 102. The blade, housing and the two deflectors are made of different plastic materials using multiple sessions of injection molding process.