When you follow the link under required items, it takes you to the page with the crystals. When you click the "Buy Now" button under the price, it takes you to a frequency selector page. That's where you specify what frequency you want. You'll want to select channel 24:72.270 MHz from the drop down list. It should then add the correct crystal to your chopping cart.

This is what you want to see in your cart: FRC824 RX XTL FM D LO 24 72270