An improved model of the constant-frequency type vibroscope t used for measuring single fiber denier is described in detail. This vibroscope has a least count of 0.01 denier, which corre sponds roughly to about 0.03 μg. weight in a 1-in. sample. The improvements incorporated into this new model pertain primarily to its speed and ease of use. A description of the important parts is included, and some illustrative data are shown.