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.
Difference between CD-R and CD ROM. Though they are the same compact discs and seemingly the same appearance, CDR and CD ROM differ with each other in terms of usability. The CDR is the disc that you will use if you have audios, videos, or any other data that you want to store by burning or writing it in to the disc.