The rear pillion pad is about 12" long and 9" wide. I just measured mine. I just ordered one of those a few weeks ago. It got here in about 4 days from Alaska. Great service! You might consider the one with gel if you do long trips. I kind of regret not getting that one but it is about twice the cost.

"Catching a yellow jacket in your shirt at seventy miles per hour can double your vocabulary" Author unknown