Unfortunately the current COMKIT(3-8) are not direct replacements for the older COMKIT1 and 2 setup.

The current COMKIT(3-8) are designed designed for use with the current ETU586 while the COMKIT(1-2) was for the obsolete ETU576.  With the current COMMOD21 (modbus) and COMPRO20 (profibus), the connector from the breaker to the COM unit uses an Ethernet adapter. This is the cable you see as current listed as COMKIT(3-8) which is available in 1.5m and 3.0m lengths.  On the COMKIT(1-2), the connection from the breaker to the COM unit used a RS232 connector, listed as the COMKIT(1-2). This was a standard 5ft length and offered the COMEXT to add an additional 5ft to this.