Will sort out measurements tomorrow. Just found a good video on Youtube. Just enter the following into their search engine. " Billy Goat Outdoor Vac KV Pro Series walk behind" You can freeze the footage or enlarge it. May help you a lot, however there are several different size bags on the market. The one on youtube is the same size as mine and can measure the bag if you still need. You will need a massive zip. If you can't access youtube, get one of the grandchildren to show you. Lot of good maintenance tips for any machine on there. Especially Hayter.
Regards Colin