This pack contains 10 double-edged stainless steel universal blades. We recommend replacing your blade every 5-10 shaves. This can vary from one person to another depending on a number of factors (hair thickness, area surface shaved, skin sensitivity, etc.) A good rule of thumb is to change it when you find that the shave is less close than the first time, or if you start to experience irritation due to a dull blade. Dimensions: app 4,4 x 2,5 cm