valve stem points inside on rear dual tires?

I was at Camping would here in Houston this morning. they now have the solid extenders for Ford & Chevy for all 4 rear wheels were 79$ this morning...!!!! I paid a lot more for mine 6 months ago on the internet. I put new Michelins on my Coach House E-450 Ford and Discount tire installed the new solid stems for nothing, and they were balanced when all was done. I have put about 2000 miles on them and they are great, so very much easer to check the air because they are solid to put air hose and check the pressure. the rubber donut that fits into outside rim stabilizes the inside duel valve stem. Next I plan on putting a pressure/temp system on all my Motor home and Towd so I can have live readings on all my Tires.