I also just had issues with two of them at my house where the battery drained down enough so I couldn't unlock the door but the light was still green.

You also have multiple exit strategies with multis here, as typically the highest and best use of them is to carve them up into condos to unlock maximum value. 

My first thought is to unlock the equity in the current portfolio (~$250k over 10 or so properties) through a portfolio loan, but then I would lose the great rates and terms of the current loans.

And, that code could be entered into the device at the entry door which would unlock the door allowing access to their rental.

If you just want to know who owns the property, in Ontario, you go to your city hall, walk into the Assessment Rolls office, sit at a free, unlocked, computer terminal, and put in the address you want to search.

It's good to know that I can just do 5% down on a new place, which would let me unlock a bunch of money for investing if I sold the condo.

Chattel for Equity - Unlock the potential of your old stamp collection, jet ski or RV.

It's vacant and unlocked, so I'm bringing a couple of people because, to be honest, I'm nervous about what I'll find as the owner doesn't want to join. 

In the break-in, the deadbolt was left unlocked and a student-tenant's acquaintances broke in assaulted the tenant in the common area.

In our market, I think there is a long term capital appreciation play, we also buy in the path of progress so in the future a few of our properties could possibly redeveloped to unlock even more upside.And I don't think you will immediately get rich with cash flow, it just doesn't happen that way, at least not immediately in most markets.Others have talked about it, cash flow is your safety net, its what lenders will look at to give you loans, its the margin you have to pay the bills.