Pen Fed's 15/15 ARM is a unique product. Although technically an adjustable rate mortgage, it adjusts only once during the life of the loan, and at the year 15 mark. With rates lower than a 30 year fixed, it is viable option for those who want a 30 year amortization and are willing to take the moderate risk of a one time adjustment 15 years from now, if they are still in the home or have not refinanced.