On 2 May 2013 at 15:22, Gary H. Harmon, Jr. wrote: > I have over 100 tube shields but the tallest one is 2 3/8 tall. I > think I need a 2 1/2 or a tad taller. It needs to be the push down > and turn type. Paint 'em, inside and out, with flat-black paint. Doing so will reduce the tube heat by at least 17%. Proven by experiment. Ken