DIN 12394 and in addition to DIN standard. With one central and one 20° side angled ground joint necks as outlined below.

Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks
Flasks round bottom, with two necks
NS jointed round bottom flasks, 2 necks