The most widely used reinforcement in modern day $$FRP$$ tennis racket is

A shaft of diameter $${20^{\matrix{ { + 0.05} \cr { - 0.15} \cr } }}$$ and a hole of diameter $${20^{\matrix{ { + 0.20} \cr { + 0.10} \cr } }}\,\,mm$$ when assembled would yield.

For angle measurement in metrology, the following pair can be used in conjunction with each other

Outside micrometer is calibrated with the help of