If I read those specs right, these rods are 98% copper and only 1.58%
Beryllium. That's the standard BerylCo alloy for making springs. You
machine it like copper to the dimensions you need (or stamp it out of
sheet which I'm more used to) and then heat treat it to form the spring.
Before you heat treat it, it works like copper so you can form any shape
you want. When you heat treat it (450 deg. 45 minutes as I remember, but
look it up) the beryllium migrates to the grain boundaries, locking them
and forming a spring. Very hand stuff and ubiquitous in the electronics
industry. All the spring contacts that hold the boards in you computer
are made from it.


Jim