http://www.smartgroups.com/message/readmessage.cfm? gid=1423922&messageid=6548&startid=6550 No, the AVID microchips use a 14 ga needle, and the male mink melatonin implants need a 12 ga needle. Close but slightly larger. The implants last for 3-4 months. Hope that helps, Jerry Murray, DVM [Sukie note: this is one I normally would think twice about copying to the FML but Smartgroups is having multiple problems recently and I know the people who needed to know this info are also on the FML, so this way if the FHL crashes they have their info for sure. Ah, the things moderators do for people... Hey, Bill Gruber, thinking about that: THANKS for all that you do for the FML and beyond! BTW, anyone who wants to know more about melatonin implants will find extensive info by searching in http://fhl.sonic-weasel.org .] [Posted in FML issue 4324]