In April, 2015, I recently bought very rare 1920-40 B100 Case XX push slide knife at Englishtown Swap Meet & Auto Show in Englishtown, NJ.

When I wander around many vendors around, I quickly spot RARE B100 Case XX Push Slide knife with tag cost $17.00. I puzzle very quiet, "$17??" Great steal! I knew It suppose be worth around $200.00. The guy sells us his things on his vendor. He seems He know nothing about Case history. I did ask him about Pushout Knife History. He have no clue about the history, he thinks it cheap and having NO clue all about the history at all. I did grab and buy it. I keep quiet. HE DIDN'T KNOW ALL ABOUT CASE HISTORY!

Now,I post to ask about M100 or B100 in few weeks ago. Because i research those any knife guide books're none. John McCain in the iKnifeCollector here too. He answer, “Michelle- According to the book "Counterfeiting Antique Cutlery" written by Gerald Witcher in association with the NKCA, page 158--- This is a very rare tang stamp circa 1905-1920 used around 1920-generally found on the M100 single blade pushout knife---The M designation indicates a metal handle of some sort, while the B can indicate Onyx celluloid--Therefore yours is a B100 circa 1905-1920 and I can see your knife easily in the $200+ range-- A very rare and seldom seen tang stamp.”

Wow.... Many, many, many thank for information to john’s answer! I knew! I can feel my gut about this rare knife..... I just thought M100 but NOT. It is B100.... He mentions my knife easily in the $200+ range? Wow! It is worth... Now I am learning this B100?? I get it. Believe it or not! Rare B100 case XX knife with tag $17.00 cost me....... You image this $17.00 for this??? Good thing i did grab and bought it. LOLOL.