Abstract: A tape-shaped product and a belt for a ball chain are provided. A tape-shaped product of synthetic resin includes a tape of a thermoplastic resin, and a preliminarily stretched fibrous member of a thermoplastic resin contained therein along longitudinally parallel edges or in proximity thereto of the tape. A belt for a ball chain, includes a tape-shaped product of synthetic resin formed by injection molding, together with a fibrous member as an insert of a resin of the same kind as that of the fibrous member so that the fibrous member is disposed along the longitudinal edges or in proximity thereto, ball-insetting holes are disposed at equal intervals, and ball-retaining projections are disposed around the holes.

Abstract: A string for a musical instrument consisting of a monofilament made of a resin of vinylidene fluoride and having the following characteristics which give good clearness of sound, good sharpness of sound and good spread of sound:(1) the diameter of the monolfilament is in the range of 0.4 to 1.5 mm .phi.;(2) the unevenness of the diameter of the monofilament is less than 5% per meter of the monofilament length;(3) the circularity of the section of the monofilament is more than 95%;(4) the specific gravity is more than 1.6;(5) the inherent viscosity is in the range of 1.1 to 1.6 dl/g;(6) the apparent viscosity with the shear rate of 1/100 at 260.degree. C. is in the range of 8000 to 20000 poises;(7) the index of double refraction is in the range of 30.times.10.sup.-3 to 40.times.10.sup.-3 ;(8) the tensile strength is more than 50 kg/mm.sup.