Extra 12v heater,any good?

I was thinking of using one of those small plug in12v heater's to blow on the rear door window [ do not have a heated rear screen and do not want to change glass as on a working landy I have found the elements are soon damaged.] Are they any good?

How are you planning on mounting it? Above the door pointing down or on the door pointing up? Either way their range/arc would be fairly small so probably wouldn't do the whole pane, that said anything is better than nothing. If your glass mounted elements are taking a bashing then I imagine a plastic heater wouldn't survive too long either.

They don't do anything

In the 1970's before rear screen heaters became standard we used to buy stick on heated window heaters, like these. https://www.ebay.co.uk/itm/classic-...468df34b9c:g:G4QAAOSwCVtb8qG9&redirect=mobile
I wonder if they is anyone still selling them. (New working ones)

I have just found this and there are others.
https://www.holden.co.uk/displayproduct.asp?pCode=080.109