there are many instruments used to measure length depending upon the size of object , Ruler is Metric instrument used to measure length. Screw gauge is also used as an instrument used to measure length in mm.
there are many instruments used to measure length . measuring tape is used to measure the length of room.
a ruler, tape measure, etc. any instrument that can measure length.
A meter stick or a metric ruler is used to measure metric length.
A metric ruler.
Vernier Calipers are instruments that are used measure length. It is an instrument that provides a digit of accuracy.
Strangely worded question, but a tape measure will measure length.
A ruler or a measuring tape.