If it doesn't come with one, pay for the accessory,,,, or even two of them.

Dedicated replacement batteries are expensive. If it's a good radio, your battery will end it's life long before the radio is ready to retire. When that happens it's the the time to pop in the accessory 'battery tray' and go with alkaline batteries till the radio is shot.

It's not usually cost effective to purchase another battery. We've used our Standard Horizon handheld for 4 years on replaceable batteries. If you can put rechargeable batteries in the tray and charge them in the radio it's the best! Usually can't do that.