What is the name of Rolex's line of quartz watches?

Rolex’s line of quartz watches was called Oysterquartz.

Rolex developed Oysterquartz during the quartz crisis, when battery-powered watches from Japanese manufacturers were rapidly reshaping the Swiss industry. Rather than simply adopt an off-the-shelf movement, Rolex designed and manufactured its own quartz calibres. The first Datejust Oysterquartz models appeared in 1976.

The range combined Rolex styling with a notably period-specific angular case, integrated bracelet and sapphire crystal. It included Datejust versions in steel, steel with a white-gold bezel, and steel-and-yellow-gold configurations. Rolex also produced Oysterquartz Day-Date models in precious metals, including references 19018 and 19019.

Oysterquartz movements were unusual for quartz watches because they used an escape wheel and pallet fork, while a stepping motor supplied the impulse. The range lasted from 1976 until 2001, although the watches disappeared from Rolex catalogues by 2003. An estimated 25,000 were made, making them relatively rare among Rolex models.