[GreenKeys] Model 15 key tops

[Jim Haynes]

I found in my Model 15 stuff a box of spring cushion key tops - the box
labelled "Master Speed Keys" and the name Speed Key Manufacturing Co,
Inc. 22 Columbus Place, Brooklyn NY.  So apparently Teletype didn't
make those keytops themselves, but bought them from this typewriter key
company.

Googling for "master speed keys" turns up only one item, a magazine titled
Special Libraries from December 1934 which announces them as a new product
"a new rubber cap to slip over your keys called the Master Speed Keys,
guaranteed to leave your fingernails unbroken."  quite likely a different
product since the Teletype spring cushion keytops date back somewhat
earlier.  But I guess long fingernails were in fashion back then as they
are now.

Sadly, the set I have is for the fractions key arrangement.