need help with inductors

first Im trying to build a 12v battery Desulfator

http://www.alton-moore.net/graphics/desulfator.pdf

I cannot obtain the 2 inductors but i have many spare "coils" , so using this program I want to make my own:

Mini Ring Core Calculator Program

now i know what a ferrite core is , its black and very hard to scratch , its also usually covered in green insulation.

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then Ive found other rings that are covered in yellow insulation , under the insulation is a soft silver material - I would like to know what that material is ?
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the mini-ring-core-calculator has the following options:
ferroxcube
iron power
ferrite ft
sefferit
air cores
unknown cores

I need to know which one to use to get the correct uH if I use the rings with the yellow isolation.

here is a picture of one:

**broken link removed**

thanks

Try this site: Ferrite Data : CWS ByteMark, largest supplier of toroids, ferrite cores, iron powder cores, MPP cores and RF cores
Go down to bottom of page, section 3 and read application notes.

They are also a good source for torroid cores.

The type and core size depends on the inductance and peak current the inductor must support. Too much magnetic flux may saturate the core if it is not physically large enough in cross sectional area.