It says that the item is reserved, what does that mean? Can I reserve any?
When an item is reserved it means that someone else went to the bot's backpack, picked the item and now is in the queue (he's waiting to buy/get it from the bot). This is done so other people aren't able to accidentally steal other user's items.
No, you can't reserve any by yourself. Items get automatically reserved as soon as you get in the queue for that item.
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Auto-Sell Hats
Automatically sell up to 100 of your eligible hats at once.
Don't worry: we won't take special items, including painted, low craft numbers, special levels, spells, killstreaks, etc.
Autosell Cards
Automatically sell up to 1,000 of your eligible cards at once.