How to trade large amounts of stuff at once?

[bluntspoon]

Newb questions. I see items for 20 keys. How does one actually do that? Doesn't the trading box only have 8 slots? How does one not get ripped off?

[Will T.]

Once you put in 7 items the trading box will increase its size to 12 slots, and it will keep increasing each time you nearly fill a row. No idea what the upper limit on items in a trade is, but I think it's high enough that most people will never hit it.

[bluntspoon]

Again, thx Will. Appreciate the time for a newb trader type person.