[Posted William Rivers Pitt with a definite agenda way beyond mere grammatical corrections.]
Memo to sign-maker: the characters you have after the "9-" are the letter "I" printed twice. Not ones. I's.
When I first tried to type on an old manual (around 1971), I couldn't find the '1' key. I had to ask my dad who said it was the capital 'I' key.
No, you use the lowercase "l" (ell).