Tube two-sided openly! The tubes can be closed for breeding purposes simply on a side with cork or filter sponge. To the removal of the boy fishes simply remove the sponge and take the boy fishes. Size of 3 middle interior diameters mittel 3,1 cm ca. 12 cm long (for middle L-Welse z.B.L201, L260, L270, L134, L181, L183 and larger Pekoltia-types) In the colors black brown-blackly.