This prototype milk meter was designed and patented by prolific Okato inventor Charles W (Charley) Maxwell. Maxwell designed the milk meter during the 1960s and during testing in Taranaki and in Australia it proved to be very accurate. The stumbling block to commercial production was that Maxwell, who was according to his family a very determined man, wanted the meter manufactured in stainless steel rather than plastic. This would have made it very expensive and prospective manufacturers were put off as a result. Other designers were not so reluctant to embrace the new material and similar milk meters became a widely used piece of labour saving equipment in the milking shed. This was one of Maxwell's last inventions before he moved into New Plymouth and retired.