patent # 2736146 was issued on Feb. 28, 1956 and the patentee assigned it to Lisle Corp.
Clarinda, Iowa
Lisle Corp. is still listed as being in the same town/city; Clarinda, IA 51632 po box 89
ph. # 712-542-5101
if you google, just put in ; Lisle Corporation.
they still list a brake cylinder hone on their web site. item # 10000
a 3 stone that fits up to 2 inches.
they also sell replacement stones. item # 10050 that are 1 1/8 inches long and 240 grit.