I purchased a TrailRider Trunk bag from Arkel and I have really love it.  The design is the most aerodynamic bag I have ever had. It has 6 inside side pockets to stow away a phone, medical supplies, extra tools or whatever you need. The inside compartment is very roomy. It is large enough for a medical kit, bike tools, food or snacks. It is fully insulated. That is a great feature!! There are two outside zippered compartments for easy access items. Waterproof zippers keep the rain out and also has an integrated rain cover. Safety features are excellent, including a blinker light strap built in the end and reflective strips all around. I highly recommend this bag!!!! Great for long or short trips.