In addition to the form factor, I really like how little extra wiring this requires. Insert on the negative wire, desolder a trigger contact and solder so that both positives are on the same contact, connect the remaining trigger contact to the FET. Done. The single extra cable is very thin, and the long narrow design of the FET means the final result isn't much wider than the negative cable. Fit in my CYMA CM.126 AEP no problem. The Perun edges it out in terms of form factor, max voltage and price but this is still a decent pick and seems more readily available.