Often these lampholders are found in Italian designer light fittings. This lampholder is an ideal replacement and comes wired or unwired. No tools are required to wire it as it has push-in terminals. 

In general, G4 light bulbs are becoming increasingly rare now with the entrance of LED. However, there are LED equivalents on the market. Be aware the replacement 12V transformers must be compatible with the G4 you use for this lampholder.