The G5i design line of 2006 was a continuation of the successful G2i line.  The inserts are a black polymer, held in with 3M VHB double-sided tape, much like Odyssey.  The heads are a high quality stainless steel, with serial number engraved on the heel side of the face.  They make great prototype specials when optimized, and can usually be found on ebay.com affordably.

These sales are for one insert only.  The putter heads in the photos are for visual only, not included.

These items are precision manufactured in the U.S.A.