In a double, where two constrictions are available, improved cylinder and modified are a good pairing, especially in fixed-choke guns. If screw-in chokes are an option, try a more forgiving match, like skeet and light modified. Shoot the more open barrel first on the covey rise, then the tighter barrel as the birds make their escape.
The CD and DVD have a single track of data in the form of a spiral, which starts as the center going outwards. The data is stored on the bumps or pits which are then read by the CD/DVD layer. The bumps/pits on a DVD are much smaller than on CD, allowing the DVD to store more data.
Similarities of CDs and DVDs. On the face of it, CDs and DVDs look very much alike. Both have a standard 12 cm diameter, and both are about 1.2 mm thick. What's even more important is that they are both optical discs, which means that the data stored on them is read by a laser. The laser goes over the pits and lands embedded onto the disc surface, and communicates a signal to the reading device that turns it into a digital code of 1s and 0s.