FLEX B4 SWIFT - ECHO The B4 SWIFT-ECHO is exactly the same as the standard B4 SWIFT, except for two simple changes to make it work slightly better for our Airline Captains. It comes with Side Pocket Echo (SPE) (water bottle not included) instead of the SPA, and the J-Hook Main Handle instead of the plain Main Handle. This bag comes with a Side Pocket Echo. An infinitely-adjustable, insulated side pocket for any size water bottle from 0.5L to 1.5L. (We got a ton of requests for a better, larger, adjustable water bottle pocket.) This bag comes with the MHJ (the special Main Handle with slots for a J-Hook), intead of the standard main handle.