The dilemma is that based on research by bladeshark and others, the Ever Ready and Rubberset company used model numbers as the suggested retail price. If a particular model sold for several years at the same price, then a trend could be established. Like the Ever Ready 140, with a retail price of $1.40. However, as prices changed, so did model numbers. Additionally, there were the odd brushes that did not follow this pattern. Like the Ever Ready 2000. There were also few models that did keep the same number, regardless of price.
The whole thing is a bit confusing. And could in part explain why there are so many model numbers.
The whole thing is a bit confusing. And could in part explain why there are so many model numbers.