Karsten Solheim applied for a patent on the now-iconic Anser on the same day that he applied for a patent on his Kushin putter. Both application were dated March 21, 1966. [And The Putter Went...PING (2017) by Jeffery B. Ellis]. They were issued sequential patent numbers.  

This an original Scottsdale PING Kushin Z-bend putter in excellent condition. PING moved from Scottsdale to Phoenix in mid-1966, so this putter pre-dates that move. Therefore, Karsten only had a few months or so to produce this putter with the earliest Scottsdale address, which explains its rarity.