The shape and dimensions of the top of a container that accommodate its closure, including the relevant thread and sealing geometry.
Also called: bottle neck finish; container finish; closure finish compatibility.
Does a neck-finish code specify the internal opening?
Not by itself. A threaded finish designation identifies a nominal width and thread family for bottle/closure matching. The internal bore is separate: I denotes the inside neck diameter, while T includes the outside threads. Check the actual drawing and dimension definitions.
This distinction matters when comparing a cap quotation with a filling-tube requirement. A nominal cap or finish width is not a measured bore clearance. Use the actual drawing and its tolerances rather than deriving the inside diameter from the first number in a finish designation.
Selected neck-finish drawing dimensions
Dimension
What it identifies
I
Internal neck diameter
T
Outside diameter including the thread
E
Outside neck diameter excluding the thread
S
Distance from finish top to the first thread’s top edge
If cap and bottle have the same finish code, is compatibility settled?
A matching code is a starting point, not complete package evidence. Liners, fitments, design variation, application conditions, thread fit and sealing-land geometry can affect the combination. Include possible liner interference in the fit review.
Keep the exact component drawings and intended liner with the sample package. Ask whether the closure engages as intended and whether the rim/liner combination supports the required sealing and opening behavior. The finish label does not itself demonstrate application torque, induction bonding or leak performance.