Came across Proviz rucksacks when looking for a new riding rucksack, these seem pretty good (20L & 30L) and a reasonable (ish) price. There’s a Guy Keston review online where he liked it but mentioned it being “a bit sweaty”, I guess this is due to restricted back air flow due to the lower back wrap around section. Anyone own one that could comment ? thanks

https://www.provizsports.com/en-gb/reflect360-waterproof-touring-backpack-green.html

Double the price but a solid piece of kit that’s 100% waterproof:

VeloDry® Waterproof Backpack – 20 Litres

I’ve had an Overboard ProVis pack for commuting before and would buy again.

I have a proviz 360 for commuting in the dark, sacrifices some stuff (pockets etc are ok but not amazing), but visibility is top notch.

Commuting – 100%

General riding bag – something else.

They look pretty good. If commuting I’d get the yellow one for when it’s not dark and people don’t have headlights on.

If you have an existing backpack you want to use for commuting, I’d recommend a hi-voz cover. I got a hump one years ago. Cheaper and takes up less space than an additional bag.

https://www.cyclingweekly.com/reviews/bike-accessories/hump-duo-tone-reflective-backpack-cover-review

Your link says, “waterproof” but the Proviz website says “Water Resistant”
I tried the Berghaus 20L and the Trespass Race 20L and preferred the Trespass
As mentioned the reflective fabric is dull grey in daylight so you might want a fluoro cover, brilliant (literally) in the dark though
The Trespass is under £20 ATM (PSA Trespass sale) similar price on Amazon, etc and it’s a UK company, like Proviz

Late to the thread but I have that exact rucksack and while it’s ok it has some egregious flaws:

1. it’s definitely not waterproof, couldn’t call it water resistant either and the included rain cover doesn’t actually fit the bag
2. there are not very many internal pockets and they are not well divided
3. it is not well padded, don’t try carrying your laptop too much
4. it’s weak. you load it up just a little bit and you’ll be breaking off the zip loops like they’re going out of fashion
5. the waist (belt) pockets are good but the hip pockets are not large and stretchy enough, making getting anything in/out a real pain.

HTH