"LARGE KEY (LG-KEY) (a/k/a LARGE GREEK KEY) --greek key design, repeated 15 times. B. C. Wills & Co., Detroit MI and Reno NV, which made these chips from 1962 or '64-1980's. At least one other place offered it recently. In 1990 The Poker Store, Stanton CA, sent me samples...........I have for sale Harrah's Reno 1963 roulette chips, white and green clay. The green ones have the inlay on one side damaged some." per Eisenstadt's website.B.C Wills & Co sold large key chips but they didn't make them, Burt Co did B.C Wills just placed the order. Made & sold are 2 different things.
Here is an order card (credit to the chipguide):
http://chipguide.themogh.org/cg_showpic2.php?cg=289713
http://www.antiquegamblingchips.com/molddesign_other.htm#md88