The Pickett and Eckel company specialized in metal slide rules, where manufacturers like K&E and Dietzgen tended to make their better rules out of laminated wood or bamboo. They were massively successful, in part apparently because of shrewd and heavy advertising, and by getting their rules in as the sanctioned rule for classroom use. They advertised that they were used on the space program, but as one observer commented, how likely is it you'd want a hunk of metal floating around in an Apollo capsule?