The large box requires the use of both shoulder clips so simply remove both D Ring attachments and clip the large box in. You can now carry enough tackle to last an entire day on the water.  If you don't want to clip the large box to the clips, you can use the included shoulder strap to carry your tackle like a satchel or over the shoulder.   The large tackle box measures 11"L x 7.25"W x 1.75"H