But to make these things work , you have to swing them pretty fast -- about 85mph to make the 5 - iron go .
The lower - numbered irons have high COR , and the higher numbered irons have very soft faces .
To make these things work , you have to swing them pretty fast -- about 85mph to make the 5 - iron go .
The lower - numbered irons have high COR , and the higher numbered irons have very soft faces .