ShapeShift.io provides users with a choice between Quick and Precise transactions.
You can do this inside Coinomi!
When the first input value (Amount) is entered, you are performing a quick transaction. You are getting a slightly lower rate, but there is no time limit and the deposit address can be reused infinite times.
When the second input value is entered, specifying how much of the receiving coin you wish to receive, you are performing a precise transaction. In this case, a timer counts 10 minutes for the deposit of the funds, during which the rate is locked. The limits are usually higher in precise transactions. The deposit address can only be used once.