Differences in woofers

Can someone tell me the difference between the 6.5 woofers in the Nht 3.3,2.9 and the 6.5 woofers in the 2.5,and1.5 Thx


On the my 2.9 it’s a cone and on the 2.5 it’s smooth just wondering what the difference is sonically 

drivers are selected specifically for the system goals and compatibility with all other parts

from 3.3 manual

"Lower Midrange: 6.5" polymer cone in 10-liter anti-modal enclosure Long-throw 2-layer voice coil 42hfz free-air resonance Fc = 67Hz, OK; = 0.66 12dB/octave high-pass at 100Hz; 12dB/octave low-pass at 320Hz"

3.3 manual

2.5 manual

1.5 manual