An oil ring for an internal combustion engine capable of securing an area of an oil-passing hole without deteriorating the strength of the oil ring. Collectively, the container assembly is useful for providing an effective barrier against gas and water permeability in the assembly and for extending the shelf-life of the container assembly, especially when used for blood collection. Using the recording apparatus, in each data recording area of a recording medium which comprises pre-pit areas and a plurality of data recording areas which are divided by said pre-pit areas, a data block which contains said added data is recorded. A gate insulating layer is formed between a gate electrode and the channel region. The phase plate comprises a support having a through-hole and an elongate member which is magnetisable in a direction along its length and which extends partially across the through-hole and which is narrower than the through-hole.