I would date the piece to the late 20's - early 30's based on the shape and decor of the enamel.
Most marks on Czech glass are typically quite unreliable for time frame...... and most of them are believed to be exporter applied, not factory marks. As an example, I have images of Loetz Ausf 140 pieces that are marked with a stamp which is definitely not a Loetz stamp and says "Made in Czechoslovakia".
Typically, hyphenated Czecho-Slovakia is supposed to point to the 1920's, but it is not something that can be used to accurately date a piece. The use of the country name Czechoslovakia really only safely indicates post 1918 production, and after that you really need to look to the glass itself to try to determine time frame.
As another example, post 1914 US law required that a stamp say "Made In", yet large quantities of glass produced in Czechoslovakia imported to the US do not bear these words, and say just Czechoslovakia.
By the late 30's and early to mid 40's many of these companies were gone or failing. Post WWI, (late 40's) it is my understanding there was not a huge amount of export due to the Soviet occupation and nationalization of the glass industry.
Craig