PENN Slammer IV 7500DX Spinning Reel.PENN Slammer IV 7500DX Spinning Reel. Product Description The Penn Slammer IV DX takes Penn's class leading Slammer IV up a notch. The Slammer IV DX has incorporated CNC Gear Technology and upgraded material. This material for the main gear and pinion is ultra durable stainless steel to give best in class durability, all while retaining the smoothness you have come to expect. The additional bearing rides in the spool so the Dura Drag(TIVl) is dually