It is missing hardness units: http://en.wikipedia.org/wiki/Shore_durometer http://en.wikipedia.org/wiki/Shore_durometer http://en.wikipedia.org/wiki/Brinell_har

It is missing hardness units: http://en.wikipedia.org/wiki/Shore_durometer http://en.wikipedia.org/wiki/Shore_durometer http://en.wikipedia.org/wiki/Brinell_hardness http://en.wikipedia.org/wiki/Brinell_hardness Also roofers commonly refer to a square of shingles:http://wiki.answers.com/Q/How_many_square_feet_will_a_square_of_shingles_cover http://wiki.answers.com/Q/How_many_square_feet_will_a_square...