If you haven't yet bothered to look for your radio manufacturer's (OEM) replacement part, let me save you the trouble: they're typically around $20.00, which doesn't include shipping. As so often happens, the replacement part nearly exceeds the cost of the new item! So this antenna is a real bargain.Figuring out the correct antenna size for your radio requires that you convert between metric and inches. Consider not just how long you'd like it to be but whether it will adapt to the length of your radio once it is folded down for transport or storage. You can put a longer antenna on your set which might improve its reception, but if it sticks out when you're trying to pack it away for travel you might regret it. I installed the 55cm (21.5 inches) on a Sony ICF-38 FM/AM ($27.95 on Amazon). Retracted, it fits comfortably on top of the unit at 5 1/2 inches.If you're not particularly handy with tools and "fixing things" then go slowly and be organized. It's unlikely you'll be able to substitute just the telescopic part at the swivel hinge, because the size of the screw is probably different.Open the radio case and remove the single screw with a wire attached that holds the square base of the antenna in place. Handle your opened radio as though it were a new born kitten. After installing the antenna, be careful to replace any extraneous parts that may have detached, like the switch or the carrying handle, before you put the case back together. Then gently tighten the screws just snug. If you try to tighten them until they don't turn anymore you will strip the threads--guaranteed. And do I have to remind you to unplug the radio before you attempt this? If you're experienced this will take 15 or 20 minutes.It took a while to get the antenna in the mail. It ships from China. How on earth they can do this at this price is beyond me. It arrived, miraculously intact, in a simple plastic bubble envelope.