Pitch Ball Electroscope....
Product Code: NLE-Export-032002 - (Pitch Ball Electroscope)Multi Spire Device Or Floating Magnets....
Product Code: NLE-Export-032004 - (Multi Spire Device Or Floating Magnets)Precision Projection Electroscope....
Product Code: NLE-Export-032005 - (Precision Projection Electroscope)