Based on the pictures, I think whichever of these measurements is supposed to be the ‘thickness’ is a little bit off …
Amazon details on item: http://www.amazon.com/Kensington-82025-Memory-Backrest-Black/dp/B00006IDA4/ref=sr_1_1?ie=UTF8&qid=1450114590&sr=8-1&keywords=Kensington+L82025F
Has the dimensions listed as 14-1/4w x 1-3/4d x 13-1/4h. Hope this helps.
Yeah, that’s a booboo.
We fixed it to
Dimensions: 2"L x 13.25"W x 12.87"H