older secondary?

[sjp]

what is the prcetage of twist on these older secondaries.what is a-1,a-2,a-3,b-1 etc.any help would be appreciated. Thank you

 

[Srxspec]

C-1 = softest
A-1 = +10*
B-1 = +10*
C-2 = +10*
A-2 = +10*
B-2 = +10*
C-3 = +10*
A-3 = +10*
B-3 = Stiffest setting