Perfect speaker mounting screw for lighter neo and smaller drivers. Serrated thread eliminates pre-boring and vibration walkout.
Washer style head, requires no washer or lock washer. #8x1-1/2 Correct for baffles with spacer rings, double thickness. 
Recex head will take either phillips or square drive.
Square drive available here preferred as there is less chance to slip and puncture a driver cone.