1.Direct replacement to your original unit. Plugandplay, direct fit, easy installation. 2.Compatible for Braun 30B 310 330 Series 3 7000 4000. 3.Compatible with Model 195S, 197S, 199S, 195, 19799199 400 FIX400; Old Model: 310, 330, 340, 4735, 4736, 4737, 4747, 4775, 4835, 4845, 4875, 4876, 5491, 5492, 5493, 5494, 5495, 5713, 5714, 5715, 5716, 5742, 5743, 5745, 5746, 7475, 7493, 7497, 7504, 7505, 7510, 7511, 7514, 7515, 7516, 7520, 7526, 7540, 7546, 7564, 7570, 7630, 7640, 7650, 7664, 7680, 7690, 7763, 7765, 7783, 7785, 7790. 4.Within 18 months your shaver will cut an average of 600000 hairs. When completing this substantive task, the cutting part will gradually wear away, and your shaving may become less compact and comfortable. Therefore, it is recommended to replace the metal foil and blade of the razor every 18 months to maintain the maximum performance of the razor and facilitate efficient shaving every day.