Just got these used and put them together. I'm 6ft and it's pretty comfortable. Pedaling lightly it reaches 20mph with assist. It's a 36 volt system and I believe the model is PL-350. See chart for distances.

I've been unable to find/verify the key for the locking system for the battery but i just leave it on the bike anyway and if it needs to be removed it can unscrewed. The battery indicator doesn't tell the truth yet but there's a procedure to reset that.