Having recently lost my expensive handheld hiking GPS due to a momentary lapse of judgement in securing it in the trunk of my car following a hike, I was determined to find a way to prevent this from happening again in the future. After a lot of online research, I landed on this retractable holster. I am using the Garmin GPSMap 66i, which is a 6.4" tall GPS. The unit itself is about 5.5" tall (not including the antenna). This Garmin unit has a perfect fit in the holster. Now, I have the pouch secured to the shoulder straps of my hiking pack, and the GPS unit securely tethered to the pouch itself. This will keep the unit safe from getting accidentally lost in the future while also making it easily accessible while out in the field. I'm very happy with this product!