Screen spline, get it at Homies. Get the largest diameter as it works best. You can get a big roll that will last a long time for under $10.00. PM me if you want me to mail you a couple feet of it.
chefchris401, I got 2 ROLLS left Im using one BUT if you need one Ill take them to PLUGFEST got 2 sizes, let me know I think there 90' long, Im still using the same roll from 2yrs ago