COBRA sells heavy-duty (22 AWG) and light-duty (24 AWG) slat cables, both CEN50 for the 36S and DB25 for the 18S slats. If you already own cables from another firing system such as ATF, for example, they are likely 22 or 24 AWG. You can run some tests to fire the maximum number of igniters you are looking to fire at the desired distance.
If you already own cables but did not purchase them from a firing system manufacturer, they will generally have much higher gauges (AWG). Higher gauge cables will dramatically reduce the number of igniters you can fire. This reduction is due to increased resistance caused by the higher AWG, for example, a 15 meter/50 ft. 30 gauge cable is the same as a 90 meter/300 22 ft. cable.
If you are running very short distances, lower-priced cables are likely OK; but as your ranges become more extended, they are not recommended and will result in no-fire situations. Again, it is suggested to test your cables to ensure they are firing correctly for the maximum number of igniters and desired distances.