一いっ生しょうもの

noun, noun which may take the genitive case particle 'no'

something that lasts a lifetime; lifetime-quality item

Refers to durable, high-quality goods (furniture, tools, bags, etc.) that one expects to use for life. Often used in marketing or when praising craftsmanship.

• この鞄かばんは一いっ生しょうものだから、少すこし高たかくても買かう価か値ちがある。

  This bag is a lifetime-quality item, so it's worth buying even if it's a bit expensive.

• 一いっ生しょうものの家か具ぐを選えらぶなら、無む垢く材ざいがいい。

  If you're choosing furniture that will last a lifetime, solid wood is best.