1. This was, as its name suggests, produced as a learner's rule.
2. Blundell also produced an identical rule except that its model number was different, S150-10, and it had no mention of the word "Classmate". This might have been an example of a maker trying to sell a product in two different markets.
3. This rule was one of the rules which the manufacturers had left on their hands when people stopped buying slide rules.

Front view

Detail - front left

Detail - front right