For how long can I reserve an item?

Reservation times may vary for different items, which is why they are always displayed on the website.
There are always two periods to choose from: one longer and one shorter (the longer period may require a larger advance payment).
If you choose the shorter period, and the period comes to an end, you may extend the reservation (though this too may involve an additional advance payment).
If a reservation period comes to an end, and a final order for the product has not been submitted, then the reservation is cancelled and the advance payment is forfeited.

A reservation is a reservation only, not an order. After the reservation period ends, you must therefore add the item to your shopping cart and complete the order submission process.