Here's another option from Amazon that we've been using for some time now.
https://www.amazon.com/dp/B07F6P86T2/ref=sspa_dk_detail_0?psc=1
Same idea, but without the cord. Works great as we have access to a 20A 110VAC plug where we store our rig, and this way, we don't have to pull out the 50A 'anaconda' cord and hook up a bunch of adapters to get some juice. Don't think I'd use these to run any high-amperage devices, though. (AC in particular). Great for running the refrigerator and keeping the batteries topped off between trips.