I can't remember if we've discussed this before but my many of my Ashkenazi customers ask me to fasten a gid to their kesher shel yad so that it doesn't move away from the bayis. I notice on some tefillin that this is done with fishing wire and sometimes even elastic, which is much easier to connect and also stronger (as the gid tends to break). Is there an inyan that this must be done specifically with Gid? And if not, why do so many people use gid if you don't have to? If anyone has looked into this or has any further info on this issue it would be greatly appreciated.