English to Spanish Tech/Engineering Furniture / Household Appliances modular holders for texti

En verdad mi duda está en "enlargement":

The invention is characterized by two types of units that can be assembled and joined together to form a chain. The invention is composed from the set of functional units and, preferably, from the end units at the end of the chain, too. End unit with three spaces holds, which can be placed on both chain sides or in any part of the chain and a function unit. Each unit comprises of an oval polymer molding having front part, end part and an intermediate part. Front part of the unit consists of oval reinforced enlargement with a boss shape having a cylindrical neck and a circular enlargement with reinforced ledges.

Lo que se muestra es como un orificio ensanchado, entonces no se si "ensanche", "ampliación" (no me gusta)...

Y a "neck" le daríais otra traducción que no fuera "cuello"?

Gracias!!