Walter is a slimline, machined aluminum responsive yo-yo that Spencer was developing for at least three years.
In 2013 he released a limited run of 100 Walter yo yos (numbered 0-99 on the inner wall) for $120 each. They shipped in a custom made wooden box, but were intended to be played with, not collected. This is something that changed with his next yo yo, Theodore, because Spencer felt the packaging of the Walter encouraged collecting over playing.
These are now very hard to find and often sell for $200+ even in fairly beat up condition.