1.1 This specification covers a disposable tube used for measuring the erythrocyte sedimentation rate, ESR (the suspension stability of red cells in diluted, anti-coagulated human blood). 1.2 The values stated in SI units This specification covers a disposable glass Westergren tube used for measuring the erythrocyte sedimentation rate. Covered by this specification are Type I (standard Westergren tube used in conventional racks only) and Type II (self-zeroing tubes used