Accurately machined with reamed bores and splined outside edges for a precision fit into the blade bore of Trend Waveform sawblades only. Extra care must be taken when mounting sawblades onto a saw spindle when using bushing washers. Only for use with Trend Waveform & Industrial Sawblades. Loose bushing washers/rings must not be used. Dimensions: Diameter=20 mm Bore=15 mm Thickness=1.8 mm Diameter Metric: 20