Aaron wrote an answer about Evernew Titanium Single Wall Mug 300 on March 30, 2012
Never mind, just did my own research on the Evernew website. It says the "300" is a double wall mug and weighs 3.4 oz. However, they also make a single wall "400" that only weighs 2.4 oz. This one looks more like the single wall version.