Abstract: An object of the present invention is to provide a yo-yo with a high rotary precision, capable of easily and reliably centering even in assembling or disassembling the yo-yo, using a bearing unit having a ball bearing with a simple configuration and high centering precision. A bearing unit (10) for a rotary toy includes: a shaft (15) including: a center portion (16) having a uniform shaft diameter corresponding to a width of an inner ring (12) of a ball bearing (11); and tapered portions (17) each extending from the center portion, each of the tapered portions being tapered toward an end portion thereof. The central portion (16) of the shaft (15) is fixed to the inner ring (12).

Abstract: A spacer is utilized in a recording disk drive, for example. The spacer is made of a mixed material at least including first inorganic powder having the particle size in a range from 10 ?m to 100 ?m, second inorganic powder having the particle size in a range from 0.01 ?m to 1 ?m, and resin material. The resin material is contained in the mixed material at an amount equal to or smaller than 40 volume % to the total amount of the mixed material. The spacer can be formed by molding. The first and second inorganic powder can closely be filled in the resin material. The spacer is thus allowed to enjoy an improved Young's modulus. If the spacer is interposed between recording disks, for example, the spacer serves to sufficiently suppress deformation of the recording disks.