Coil Spring Holder

Diameter (first number):
15 = 1.5mm used for Small Head (SH) Type and Long Head (LH) Type
20 = 2.0mm used for Circle Head (CH) Type and Fixation Head (FH) Type
25 = 2.5mm used for Bracked Head (BH and BH-L) Type

Lenght (second number):
 8 = 8mm
13 = 13mm 

Forces:
L = Light Force
M = Medium Force
H = Heavy Force