The CDN 405M40-5 is designed according to figure 5 and 6 of IEC/EN 61000-4-5:2017, it’s used for test unshielded unsymmetric communication line with transmission rate up to 100 Kbit/s. Max. surge test is 6 kV.
These are compatible with most any existing surge generator on the market producing reliable output. The EMC Shop stocks the CDN 405M40-5 and can provide accredited calibrations immediately.