The new models are part of a family of cell phones Motorola is building around the Razr, which has helped the company revitalize its brand in the last few years.
With competitors like Samsung having followed suit with their own skinny phones, Motorola hopes to keep up the momentum of the Razr with new models inspired by its style and four-letter name. Motorola has sold about 50 million Razr phones since they were first launched in late 2004.
The 42-millimeter-wide Krzr flips open like the 54 millimeter-wide Razr but is slightly thicker, as it has a better 2-megapixel camera and space for extra storage for up to 500 songs.
The Krzr, made of magnesium, polished chrome and hardened glass, also has a reflective surface and will come in two colors: gray and blue. It is to be sold worldwide by the end of the year.
The narrower phone should help the company attract new customers including women, said Tracey Koziol, an executive in Motorola's handset division.
"For people with smaller hands, it does probably fit better than the Razr, especially for Asian customers and ladies," said Koziol, adding that most cell phone carriers around the world have shown interest in the product.
"We expect very good take-up," she said.
Koziol said the Krzr would probably sell at about the bottom of the high-end price range, but she declined to give a specific figure. Analysts often describe phones that sell for more than $250 as high-end, and $125 to $250 phones as midtier.
The Krzr will be available for networks running on GSM, the dominant global wireless standard, and CDMA, a popular phone standard in the United States and parts of Asia.
Motorola also unveiled the Rizr, which is 46 millimeters wide and slides open. It gives users the option of turning the phone sideways when it is closed to take landscape photographs using a dedicated button for its 2-megapixel camera.
Available in blue, red and black, the Rizr will initially be sold just to operators using GSM networks. It is expected to sell in the midtier price range.
Motorola also unveiled three phones for high-speed wireless services. The Razr XX and the Razr Maxx will work on networks based on HSDPA, a faster version of GSM, and will allow users to stream video or music to the phones over the air.
The Razr XX is expected to price in the midtier range while the Maxx, which has room for extra storage and a 2-megapixel camera, is expected to sell in the high-end range.
Motorola also debuted the SLVR L7c, a candy-bar phone also inspired by the Razr that will run on EV-DO, a faster version of CDMA.