A tubular food casing based on regenerated cellulose, which casing may be fiber-reinforced, is coated on its inner surface with a copolymer which includes 50 to 84% by weight of vinylidene chloride units, 2 to 20% by weight of acrylonitrile units, 1 to 10% by weight of acrylic acid units, and 1 to 47% by weight of alkyl acrylate units. The side wall is in contact with the interlayer insulation film. Alternatively, the junction is in the a-b plane direction. A roughfine motion focusing operation portion is provided for operating the roughfine motion focusing mechanism and includes a second rough motion handle and a second fine motion handle provided near a front end of the base portion. The input data and the additional data are separately received to be operated so that the circuit scale of the filter is reduced.