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Mountain Briefcase Expandable 35L Travel Backpack

Mountain Briefcase Expandable 35L Travel Backpack

Rocky Mountain Underground

  • Sale
  • Regular price $249.00

Key Product Features

  • Versatile travel backpack, rugged and refined enough for any adventure, on or off road.
  • Excellent padding, weight distribution, and multiple ways to carry make it great for long hauls.
  • Expandable and organized storage takes you from 35 to 50 liters so you can use this bag on trips of any duration.

Customer Reviews

Based on 1 review
Awesome Luggage Backpack

Awesome luggage backpack for road trips or flights. Love the clamshell opening, tough exterior, and good looks.

Mountain Briefcase Expandable 35L Travel Backpack

Adventure knows no bounds with the RMU Mountain Briefcase Expandable Travel Backpack. This versatile travel backpack can do it all. Made from premium materials designed to withstand the elements on the toughest treks or alpine adventures. The highly durable TPU coated material is extra tough and weatherproof. 35L of packable space offers plenty of room for a weeklong trip while still fitting in an overhead bin. When in need of additional space, this backpack expands all the way up to 50L of total space. The interior is loaded with organization features including sidewall pockets, a removable compression strap, and a false bottom to hide valuables. Store your gear confidently with a padded laptop sleeve, storage dividers, and a stashable elasticized sling on the outside for shoes or a light jacket. This unique expandable backpack will keep you organized on trips of any length, last a lifetime thanks to the premium material and construction, and look awesome the whole time.



  • 2 ways to carry; briefcase style via the grab handle with the shoulder straps stashed or on your back.
  • Premium materials include TPU coated weatherproof external, 150D polyester liner, and aluminum hardware.
  • Accordion-style expansion from 35 to 50 liters so it can be used on trips of any length.
  • Multiple internal pockets, storage divider, false bottom for hiding valuables, and a padded laptop sleeve to keep you organized.
  • External small zipped pocket.
  • Front side elasticized sling offers additional external storage and tucks away when not in use. Great for strapping a light jacket or extra shoes to the outside of the bag.
  • Stash the shoulder straps in the back panel to check it or carry as a briefcase.



  • Green: Canvas with polyurethane coating, 150D polyester liner.
  • Black: 630D TPU coated nylon, 150D polyester liner.



  • 22” H x 15” W x 5” D | Volume 35 liters
  • Expanded: 22” H x 15” W x 8” D | Volume: 50 liters


Free domestic shipping for all orders over $49.

Depending on the product and availability, your order should ship in 2-5 business days. You will receive a confirmation email with a tracking number and the carrier when your order ships so you can track your package and know exactly when to expect it. Average transit time is 3-5 business days.

We do not offer expedited shipping, but if you need your delivery rushed please contact us at and we will attempt to expedite your order.

Currently we do not ship internationally.

If you bought multiple items they might ship separately.


If you are not happy with your purchase for any reason in the first 30 days, contact us at and we'll help you initiate a return.

Please note that items must be unused with the original packaging intact in order to receive a refund. Refunds will only be processed after the item is received and its condition is verified.

Return shipping is the responsibility of the purchaser.

Our Shipping & Returns page has all of the details.

Our Promise

We want to make sure you’re happy with your product, your purchase, and everything in between. We hope you’ll love every product you buy from Flashpacker Co but understand sometimes things go wrong. When that happens we’ll do everything we can to make it right.

Check out our Satisfaction Guarantee page for the full details.


Rocky Mountain Underground


Rocky Mountain Underground

RMU started with humble beginnings building skis for friends in their basement. Word got out about their high quality and innovative designs and before they knew it everyone was looking for RMU skis. RMU has grown into a reputable ski and snowboard manufacturer building exceptionally high quality and sustainable products. Their skis are still produced by hand with a low waste and high durability emphasis in every product.

This commitment to quality extends to Rocky Mountain Underground bags and gear. Every bag is uniquely designed to keep you moving and enjoying the outdoors. We love the exceptional quality and innovative designs that go into every RMU bag. When you need reliable gear for outdoor adventures, look no further than Rocky Mountain Underground.

Product Warranty

Every Rocky Mountain Underground bag is backed by a lifetime warranty against defects in manufacturing.

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