Finally found my reference for these. Here it is:

These are Bezirksstempel, or district cancels. They were introduced by the Reichspost in 1893 as a security stamp for financial transactions. For this reason, they are commonly seen on money orders, payment cards, and cash receipts. It was typically used as an off-stamp cancel, but they can sometimes be found on the accompanying stamps.
The size is typically 12.5-14mm wide by 14-15mm tall. Machine and handstamp versions exist.
The top number indicates the district.
1 = BZ-1 District, Prag (Prague)
2 = BZ-2 District, Pardubitz (Pardubice)
3 = BZ-3 District, Brünn (Brno)
4 = BZ-4 District, Troppau (Opava) -- converted to BZ-3 Brünn in the fall of 1940.
Of those pictured in this thread:
1/996 -- Pschestitz (P#345;eštice) -- known usage around 3 Dec 40
2/70 -- Böhmisch Bela (#268;eská B#283;lá) -- 15 Mar 39 to 7 Jun 42
3/82 -- Brünn 12 (Brno 12) -- 3 Sep 40 to 31 Nov 42
?/354 -- need the district number
1/37 -- Klattau (Klatovy) -- 8 Sep 39 to 27 Jun 44
4/250 -- Mährisch Ostrau 8 (Ostrava 8) -- around 19 Sep 40
4/140 -- Mährisch Ostrau 6 (Ostrava 6) -- around 10 Sep 40