This is 27 inches and attaches to the bottom of the sliding glass door and hooks on and glides on the channel attached to the tub.
Bob from SWISCO responded:
July 20, 2020
We don't carry a bottom shower door guide in this length, but if it installs with hooks to the bottom of the door frame you might be able to use our 10-139 guide pair as a replacement. This blog article here goes into more detail about this product.