... filling, leaks and blockages in stopcock mechanisms.1644B BURETTE with blue line on milk white background,rubber tubing connection, glass ... 1644B-03508600.10.1120GS-1644B-041008600.20.2120 BURETTE with blue line on milk white 1645A background,straight stopcock Cat. ... 1645A-03508600.050.160GS-1645A-041008600.10.260 BURETTE with blue line on milk white 1645B background,straight stopcock Cat. ...