When you setup premiums on a donation form, they are associated with specific donation levels so that you are only eligible for a specific premium if you donate a specific amount. However, the user-entered amount donation level is handled a bit differently since the donation amount is variable. Whenever the user-entered amount donation level is used and there are premiums associated with the donation form, the actual amount entered will be matched with the highest donation level that is less than or equal to the user-entered amount and premiums for that donation level will be shown. So for example, if you have donation levels of $10, $20, and $30 that all have associated premiums, if I enter $15 in as a user-entered donation amount, I will be shown the premium options for the $10 donation level. However if I enter in an amount less than $10, I won't be offered any premiums even if there are some associated with the user-entered amount donation level.