I received my replacements a few days ago.
Oddly, the replacements are 6 pounders while the originals were 3.5 pounders....
FireExtinghishers.jpg
(The one from my kitchen, the one from my camper, and the two replacements)
The other thing new to me is the idea of a 12-year lifetime.... (see red text)
FireExtinguisherLabel.jpg
They both have the year 2018 embossed on the bottom of the cylinder.
They're Kidde model number FX210W and are UL rated 2-A:10-B:C.
The old cylinders were about 3 1/4 inches in diameter and the extinguisher has maximum width of 6 inches at the handle. The new ones are about 4 1/2 inches for the cylinder but with the hose and handle, maximum width is 8 inches. Height is 13 1/2".