One of the biggest problems with working in the field is bringing all your tools and keeping them organized.  Olympia has a portable cart that folds in seconds and allows you to have 3 levels of storage at up to 150 lbs.  The cart weighs 21lbs and can be stowed just about anywhere, including the trunk of a car.  It is only 8″ wide when folded.  For the service tech this cart is a no brainer.  You can put all your parts on the cart and keep them organized.

You can get the Olympia Service cart for around $90 over at Amazon.com