Easy to install.Clean the razor before installing.Please make sure well your razor model.fit:For Braun Series 5 8000 51S Replacement Foil Head & BladeCompatible with:For all 51S models including:Type: 5643, 5644, 5645, 5646, 5647, 5649, 5751, 5757, 5758Model NO: 8970, 8975, 8985, 8986, 8987, 8990, 8991, 8995,8595, 8795, 8581, 8583, 8585, 8588, 8590, 8781, 8783, 8790, WF1s, 510, 550, 560, 570cc, 590cc,530s-4, 550, 550s-3, 550s-4, 550cc-4, 560, 560s-3, 560s-4, 565cc-4,570cc, 570cc-3, 570cc-4,590cc, 590cc-3, 590cc-4, 8385 C&R,8374, 8377 - Series 5, ContourProNote: The method of checking the replacement part number of the shaver is as follows: Push open the for shaver's sideburns trimmer and you will see the replacement part number (for example, 10B, 30B, 32, 51S, etc.)Grid cover: 4.4x2.5x2cmKnife head: 3.1x1.7cmColour:SilverMaterial:Nylon+stainless steelPackage Contents:1 x mesh cover1 x knife head