The 30SPK/2 Mechs have solder connection on the rear.

Please go to the following links below and check under the Documentation Tab for more information.
Australia - https://www.clipsal.com/products/detail?CatNo=30SPK/2&itemno=30SPK/2-WE&backto=/search?q=30SPK&tab-document-1=0
New Zealand - https://www.pdl.co.nz/products/detail?CatNo=30SPK/2&itemno=30SPK/2-WE&backto=/search?q=30SPK