Here's a link to a previous T5 Pinkerton discussion.
http://www.net54baseball.com/showthr...t=T5+Pinkerton
In addition, in 1986 Lew Lipset wrote on page 26 of his Volume 3 - 20th Century Tobacco Cards---1909-1932...
"T5 Pinkertons can vary in size, both in the size of the mount, the type of the mount and the size of the picture. Most desired and most aesthetically appealing is a 3 3/8" x 5 1/2" photograph without a white border adhered to a 4 3/4" x 7 3/4" thick mount which is embossed around the picture area. T5 photographs are often found off the mounts and can be found on less substantial backings which approach construction paper in nature. These are also believed to be "original" mounts and can only lead one to believe that the Pinkerton Company didn't care to control the quality of their product. Both the heavy cardboard and "construction paper" backings could vary with respect to color."
Patrick