The PING 3A putter was first designed in in 1959. It was a mallet putter with a sight line cast into the top. According to the first year's orders in 1959, the 1A putter was the overwhelming choice. Out of 454 confirmed orders received by PING in 1959, 427 of those orders were for the 1A, but only 3 orders were for the 3A putter [And The Putter Went...PING (2017) by Jeffery B. Ellis]. That surely goes a long way in explaining the rarity of this putter.
This putter is stamped with PING's early Scottsdale address. PING moved from Scottsdale to Phoenix in mid-1966. This putter is in very good condition.