PET bottle necks: PCO 1881 (soda, 28 mm) and 38 mm (milk/juice) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/pet-bottle-necks-pco1881/  (CC BY 4.0)
Basis: PCO 1881 (ISBT) neck finish; 38 mm three-start finish per ISBT; bottle body sizes typical
Catalog version: 2026-10-20

Sizes: see table below
- Soda / water bottle neck (PCO 1881): thread OD 27.43 mm, thread root 24.94 mm, 2 mm pitch single-start with 3 thread turns, neck height 17 mm from the support ring to the top, support ring Ø33 mm. Cap ID 28 mm. The older PCO 1810 is 21 mm tall with the same thread.
- Milk / juice bottles: 38 mm finish (thread OD 37.5 mm, 3-start, 1.8 mm pitch, 10 mm tall). Water-cooler jugs are 55 mm.
- Bottle bodies: 500 mL Ø65 × 200 mm; 1 L Ø80 × 270; 2 L Ø110 × 310, PET wall 0.3 mm. A printed PCO 1881 cap (thread modeled as a 27.9 mm bore with a 2 mm pitch groove) screws onto any soda bottle: pressure vessel to ~8 bar, the clear cylinder of a water-rocket or a pressure test rig. Never heat PET above 70 °C.

finish  thread_od_mm  root_mm  pitch_mm  height_mm  cap_id_mm
PCO 1881 (soda, 28 mm)  27.43  24.94  2.0  17.0  28.0
PCO 1810 (older 28 mm)  27.43  24.94  2.0  21.0  28.0
38 mm 3-start (milk/juice)  37.5  34.0  1.8  10.0  38.0

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Plastic bottle — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Plastic_bottle
- ISBT: PCO 1881 finish drawing (International Society of Beverage Technologists) — PDF — ISBT publication [verify license at link] — https://www.threadspecs.com/
- Long Earth Society: Engine builds (videos and write-ups) — web, video — LES site — https://longearthsociety.com/engineering/

Xem Studio scan: not needed; this is a published standard. The sheet is the geometry.
API: https://xemstudio.com/api/geometry?object=pet-bottle-necks-pco1881