0.125<0.18, so no number can be both less than 0.125 and greater than 0.18.
However, a number can be less than 0.125 or greater than 0.18.
You write this as x<0.125 or x>0.18 (if x is the number). In other words, x can't be between the two limits.
0.125<x<0.18 means that x lies between the limits: x>0.125 and x<0.18. An example would be x=0.15.
(The chevron's point points to the smaller or lesser quantity. 0.125<x means that 0.125 is the smaller quantity and is the same as x>0.125.)