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Black Diamond
Theorem 30L Backpack

5 out of 5 stars
8 Reviews
Current price: $74.96 Original price: $99.95
25% off
Color:Sun Yellow



Theorem 30L Backpack

A 30-liter daypack that blends functionality with unparalleled style, the Theorem 30 holds everything you need for lifes multi-purpose missions. The internal organizer features a key-leash and zippered mesh pockets, while the electronics sleeve can be accessed both internally and externally. Two external stretchy side pockets hold water bottles, climbing shoes or any other gear you need, while a front-mounted daisy chain adds attachment options. the main pack body is built from 100% recycled fabrics.

Responsible Collection
100% 840D recycled polyester, recycled mini ripstop nylon
30L (1831 cu in)
Shoulder Straps
S-curved, padded
Waist Belt
Hydration Compatible
2 side stretch, 1 front zippered accessory
Gear Loops
1 daisy chain
side straps
Claimed Weight
casual, travel, commuting
Manufacturer Warranty
1 year

Overall Rating

5 based on 8 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 0 reviews
3 Stars - 0 reviews
4 Stars - 0 reviews
5 Stars - 8 reviews

What do you think about this product?


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5 out of 5 stars

July 30, 2023

Stylish Backpack

Who says versatility can’t be stylish? I mean what a great bag, this holds everything you need for the day, yet provides amazing comfort if you decide to take that bulky laptop with you on a hike, for instant online meetings. If you want to let your co-workers in the office know that you do cool things on the weekend like hike and rock climb, then this is the bag for you!

Jacob M.

Originally reviewed on

5 out of 5 stars

March 5, 2023

Great Quality

I've had countless backpacks over the years. This one is definitely my favourite. It has loads of pockets and storage options to keep everything organized. The laptop pocket is a good size (I don't know how big my laptop is, but it's one with a number pad, bigger than one I had years ago). This bag fits my laptop with one or two inches to spare. Compression straps on the sides help keep everything tight on lighter day. Overall the bag feels good quality. The zippers feel sturdy and smooth. I've been using it for a few months now and it still looks brand new. I'm very happy with this purchase.

Roberto B.

Originally reviewed on

5 out of 5 stars

March 4, 2023

Great pack.

Replaced an older, worn out Patagonia backpack. Great bag, only update is suggest might be an exterior sunglasses pocket at the top? No issues other than that.

Dylan W.

Originally reviewed on

5 out of 5 stars

March 2, 2023

Back to school

This back pack has been the best part of going back to school. I would appreciate a top sunglasses pocket, but overall a well designed pack

Emerson F.

Originally reviewed on

5 out of 5 stars

September 21, 2022

Great Pack !

I love this pack. Very well thought out for it's intended range of uses. Lap top storage is awesome and plenty great storage for an active lifestyle at the same time!

Lee B.

Originally reviewed on

5 out of 5 stars

September 19, 2022

Look good, feel good!

I purchased this pack for work and travel, and so far it hasn't let me down. There is plenty of space in the main compartment to stuff jackets, fleeces, or other random clothing items, and my laptop, iPad, and notebook have perfect spots as well. I love the side compartments for water bottles and coffee on the go.

Amanda C.

Originally reviewed on

5 out of 5 stars

August 30, 2022

Great Backpack

I used this backpack for school and it fit everything and was great. Thank you black diamond!!

Sascha T.

Originally reviewed on

5 out of 5 stars

August 24, 2022

Great bag!

Plenty of pockets. And one of the most comfortable shoulder straps I’ve ever owned. Highly recommended

Dan C.

Originally reviewed on