The purpose of inserting the needle and retracting it slightly is to make a pocket under the skin. The transponder exits the end of the needle completely, meaning the full length of the transponder (12mm) extends out past the tip of the needle during deployment. If you insert the needle and do not retract, then when you depress the plunger to eject the transponder, it will have to make it’s own way under the skin, which could result in a sideways or misaligned placement. The ideal placement is parallel to the index finger metacarpal bone. It’s not necessary to retract the needle to the point it’s almost coming out of the incision site, just 10mm or so would be enough.