I have traditionally had a conventional PDF with the zipper on the front. The Ninja has a side entry with a dual clip in system. After a couple of uses I have found that I really like the side entry. The Ninja is true to size and is very well constructed. I have used this mainly for kayaking but plan to try it for paddle boarding.The design makes it very comfortable and compliments the seat that I have in my kayak. Would highly recommend this PDF to both new and seasoned water sports participants.