These are very nice Fly Boxes, See Through front and back covers lets you see your flies. 

The box has a center leaf with micro slit foam on the front and back sides. There enough room for both Dries and Nymphs without them getting squashed by the lid.

These boxes have a water proofing seal, so will help protect your flies from getting wet if you do drop it in the river, and it will float so you can hopefully retrieve it if that does occur.

Large & Medium sizes

The large size will fit in standard vest pockets