Calibration services of five countries from the Sistema Interamericano de Metrología (SIM) region are compared through measurements of surface roughness and step height standards. A surface roughness standard with a nominal roughness average (Ra) value of 0.2 µm, a surface roughness standard with a nominal Ra value of 3 µm and a nominal spatial wavelength of 99 µm, and three step height standards with nominal values of 2.55 µm, 0.38 µm and 0.03 µm are compared. Special attention is paid to the influence of the long wavelength cutoff ratio of the measurements. Results are reported for Ra, maximum height of profile Rz, mean width of profile elements RSm, and step height d, depending on the sample measured. The initial reported results show that the laboratories agree on all of the measurements within their stated and published uncertainties. Observations are then discussed about the definition of Rz, the effect of instrument noise on Rz, the different step height parameters d and Pt, differences between the laboratories in reporting Type A statistical uncertainties, the method for calculating the uncertainty of the reference value, and the importance of accounting for correlations between the reference value and individual lab values when calculating the degrees of equivalence. After corrections and reanalysis the laboratories still agree well considering their stated uncertainties.

This supplementary comparison concerns the calibration of gauge blocks by mechanical comparison, which is a technique of paramount importance as it is at the highest level in the traceability chain of length for most countries of the American Continent. This comparison is designed to support the submitted CMC claims of these countries.The measurand is the central length of several gauge blocks as defined in ISO 3650 and the circulated gauge blocks were used for two comparisons carried out in two stages: the first stage, SIM.L-K1:2007, Calibration of gauge blocks by optical interferometry (2007–2010); the gauge blocks were also measured by mechanical comparison for those NMI also participating in SIM.L-S6:2007; the second stage, SIM.L-S6:2007, Calibration of gauge blocks by mechanical comparison (2010–2011) for the participants that measured only by mechanical comparison.In this second comparison there were 16 participants, 14 from the Americas, and 2 invited NMIs from other regions. The circulation in the second stage had 10 participants. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).