The phrase "addition to its line" is correct and usable in written English.
It can be used when referring to the expansion or enhancement of a product line or offerings by a company.
Example: "The company announced the addition to its line of eco-friendly products, which will be available next month."
Alternatives: "expansion of its range" or "inclusion in its lineup".
The SVB-100K Silent Bass is Yamaha's latest addition to its line of instruments that allow musicians to practice in privacy using headphones and, more important, not bother others with that awful movement by Berlioz.
At an event in Brazil this morning, Lenovo announced the latest addition to its line of modular handsets.
In addition to its line of desktop and notebook PCs, Dell offers network servers, data storage systems, printers, Ethernet switches, and peripherals, such as displays and projectors.
Staging up to compete with Dell and Apple, HP has announced a 30-inch addition to its line of widescreen LCDs.
Google has added a notable addition to its line of "Go" edition apps – the lightweight apps designed primarily for emerging markets – with the launch of Gmail Go.
Sales of Saab's updated 9-5 flagship model have been growing steadily, and in the coming weeks it will start marketing its first crossover-utility vehicle, a critical addition to its line-up, especially in America.
In addition to its lines of denim and sportswear, Hilfiger will show its women's runway line on the fourth floor.
In addition to its lines of hair care and styling products, the company operates a nationwide network of cosmetology and barber schools.
On Thursday, Amazon.com is expected to introduce additions to its line of e-readers and tablet computers, and negotiators for the United States and eight Pacific Rim nations will resume talks in Leesburg, Va., about protections for intellectual property.
The company just announced additions to its line of digital watches that can snap digital pictures and load them to a personal computer.
At Computex Taipei 2007, SanDisk showed off its two new additions to its line of solid state drives (SSD): SanDisk 1.8-inch 64GB UATA 5000 and 2.5-inch 64GB SATA 5000 SSD products.
