Twin inductors for IMD pin pointer

[Bobman]

This could be a stupid question but.....
I am making the pin pointer featured in the excellent 'Inside the metal detector' and it uses 2, two pin inductors side by side that have to be in anti phase to each other. As they are insulated, with no polarity markings and otherwise identical how do I ensure this?
The text says it will not work otherwise but my circuit might not work at first anyway!
Thoughts appreciated.

[Carl-NC]

If they are identical axial inductors then they will be wound consistently in the same direction. If you connect them in series and then fold them over then they will be correct no matter which way you connect them. If you are using radial lead inductors then you need to figure out the polarity of the leads.

[Qiaozhi]

The inductors used in the ITMD pinpointer were radial types. There were no markings to distinguish the polarity, but the inductor had 472k printed on the top so you can use that as a guide.