Oura has filed another US lawsuit against Ultrahuman, this time targeting the company’s new Ring Pro and seeking to stop sales of the wearable in the American market.

The legal action follows Oura’s earlier patent case against Ultrahuman over the Ring Air, which resulted in the product being removed from sale in the US.

Ultrahuman subsequently redesigned its smart ring and introduced the Ring Pro, arguing that the new model addressed the issues raised in the earlier dispute.

Oura is now alleging that the Ring Pro infringes two patents covering elements of the ring’s design and internal construction.

The company is seeking financial damages as well as a court order blocking further Ring Pro sales in the US.

The latest case has been filed in a federal court in Texas, where Ultrahuman’s US manufacturing operations are based.

SVTronics, the contractor producing the Ring Pro in Plano, Texas, has also been named as a defendant.

Ultrahuman has maintained that the Ring Pro was specifically redesigned to avoid the patent issues raised in the original case.

The company has also pointed to approval from US Customs and Border Protection, saying the redesigned product was cleared for import and does not infringe Oura’s patents.

One of the patents now cited by Oura was issued just two days before the latest lawsuit was filed.

For now, the Ring Pro remains available in the US unless a court orders sales to stop.

Ultrahuman products also continue to be sold in other markets, with the current dispute focused on the US.

The case adds another layer to the increasingly competitive smart ring market, where Oura and Ultrahuman are among the most prominent brands competing on health tracking, battery life and wearable design.