These are standard 1/8 inch (3.1mm ) outer diameter Aluminum tubes. The tubes made with tight tolerances and have a high quality exterior finish Inside diameter is 1.9mm to fit 1.8mm liner tubes. Available in variety of lengths. Each Pack Contains: 60 Tubes plus plastic insertion tubes and junction tubing. Packaging : 9mm  - package includes : Aluminum tubes: 60pcs . + liner tube :120cm . + Junction Tubeing :90cm . 13mm  - package includes : Aluminum tubes: 60pcs . + liner tube :150cm . + Junction Tubeing :120cm . 19mm  - package includes : Aluminum tubes: 60pcs . + liner tube :180cm . + Junction Tubeing :120cm . 25mm  - package includes : Aluminum tubes: 60pcs . + liner tube :240cm . + Junction Tubeing :120cm . 38mm  - package includes : Aluminum tubes: 60pcs .+ liner tube :300cm . + Junction Tubeing :150cm . 51mm  - package includes : Aluminum tubes: 60pcs . + liner tube :360cm . + Junction Tubeing :150cm . 6 Sizes Kits - package includes : Aluminum tubes: 60pcs (10pcs each size).+ liner tube :240cm .+ Junction Tubeing :125cm .