Some of these technologies are VRC (vented reinforcement collar), Elevated Frame-Cooling and Floating Cone Attach Method. The 13W1v2-8 works best in small enclosures making it ideally suited for smaller or hard to fit vehicles. The mounting ring is removable and customizable making installation of the speaker grille-mesh simple with no extra required hardware. (Grille mesh inserts are sold seperately.) This also allows the ring to be painted to match the desired look of the car interior. The optimum power range for the 13W1v2-8 is 125-250W, and running over 350W will void the manufacturers warranty. To go over 350W, you will need to upgrade to one of JL's superior sub-woofer lines. The 13W1v2-8 has a free air resonance of 21.9 Hz with a nominal impedance of 8 ohms. However, like all the W1v2 sub-woofers, there is a 4 ohm version which is sold as the 13W1v2-4 allowing consumers to pick the sub-woofer which suits their audio set-up.