The provision applies to assets that are manufactured, produced, constructed, or assembled by the taxpayer NOT for sale but are later sold either way, and that are similar to other assets that the taxpayer manufactures, produces, constructs, or assembles for sale.
Basically even if assets are held as capital assets, they may still be subject to paragraph (jA) of the gross income definition and included in gross income if they are similar to other assets that the taxpayer manufactures, produces, constructs, or assembles for sale.