Speaker Grill Cover must be 170mm or smaller
Known grills that fit;
https://www.amazon.com/Rockford-Fosgate-P165-SE-6-5-Inches-Component/dp/B00XAINY2K
Pioneer TS-G1645R 6-½" / 6.732"
Rockford Fos Gate R165X3 6-½" / 6.732"
JL Audio TR650-CXi 6.5" / 6.732"
*ANYTHING OVER 171.45mm GRILL COVER WILL NOT WORK
171.45mm = 6.75" WHICH IS THE DIAMETER OF THE ENTIRE OPENING