Isoelastic porous meshes useful in hernia repair have pores that remain open under physiological loads. The lowpass filter is mounted on a driving mechanism that moves it in the direction parallel to a light-receptive surface of the CCD. A foreaft position sensor is located between one of the foreaft extending arms and the respective saddle. The indicia has a first visual state and a second visual state, the indicia being more noticeable in its second visual state than in its first visual state. The roller bracket assembly may be pivoted, and the top bracket may be connected to the bottom bracket in a different position further from the cutting reel, so that an attachment such as a conditioner may be installed between the front roller and the cutting reel.