What matters is that it can hold a 10 x 5 x 5 size router, does not block radio waves and does not interfere with the wifi.

Buy a direct mailing list and start sending out letters?

So if you have your heart set on that, then the next thing is how you are going to buy, meaning off market, like yellow letters and the like, or more of a retail strategy.

Also, remember - letters do help!

About to submit a letter of intent/offer.  

I received a letter from a cleaning service, envelope is addressed to me.

It reminds me so much of the Eastern Block under the Soviet Union where you couldn't control your own private property and everyone operated in fear, knowing their neighbors could report the slightest violation and destroy their life.

If you buy a property the county will send you a letter asking what you paid.

When I send offers, I always include a letter about my clients and I make sure the agent or seller can get a good summary of what we are offering right there in the email.

I started a driving for dollars mailing list and sent letters.