It has a zipper that will expand the bag to 21 L, a hidden mesh water bottle pocket, a separate padded section for up to a 16 inch laptop and a tablet, a strap so you can carry it over your luggage handle, and it’s made of durable water resistant fabric. Lots of internal pockets to hold all your gadgets and an RFID pocket to protect your credit cards from being scanned. It also has a couple of add-on straps so you can carry your jacket on the outside if you want. And the back is molded so that there is some airflow. It has been my favorite bag for a long time!
Plus it looks professional!
Do a search as there are lots of really great reviews and demo videos.