What is sight to set up for letter writing?

"Sight to set up for letter writing" is a company that I started about 4 years ago. We specialise in the manufacture of spectacles for people who can't write letters due to the fact that they're as blind as bats. We are the one-stop-shop for all your glasses needs. Buy one pair, get another free until the end of the month.

I don't understand.

If you want to write a letter, you get a pen and paper and write.

Yes, you need sight to be able to see what you're writing but 'set it up'?

Or do you mean a site?  A website?  Most people just use Word or a similar application.