ALRO circular Slide rule case Muiderkring 1960 Holland

This small round slider rule is marked De Muiderkring and Bussum-Nederland and is two sided. The Muiderkring was a group of Radio amateur enthusiasts from Holland. It is in good condition with chromium plating on the centre of both sides in tact. Both sides show some darkening from use and age, but it is still completely readable and functions like it should. The black rim is also in tact. It comes in the original leather case that is complete but coming loose at the seems. I assume it is from somewhere in the 1960’s and it is made by ALRO from the Netherlands / Holland. This model has various rare scales like V1 V2 W1 W2 Neper, MC/s, pF and N. Both sides have a see-through disc with hairline that acts like the cursor. It measures ca 6 cm or 2 3/8 inches in diameter. Check the attached video on how to work your vintage man tool : slide rule operation instructions!