Beleaguered smartphone maker Motorola is releasing two flagship handsets, the Moto Z and the more expensive Moto Z Force. The two designs show Moto's parent company, Lenovo, is embracing the modular smartphone trend.

Pacing the stage at a press event in San Francisco, Lenovo product engineer (yep) Ashton Kutcher called the Moto Z "a redesign of the phone from the ground up," comparing it to groundbreaking Motorola handsets like the StarTac and Razr.

They don't look quite as revolutionary as those market-upending devices. The new Moto Z offers mostly high-end specs: 5.5-inch Quad HD display, Qualcomm Snapdragon 820 processor, 4GB of RAM, and lightning fast charging. There's a 13-megapixel camera on the back, and a 5-megapixel sensor up front. It's a mere 5.2mm thick. Remember when the first Droid Razr was so thin? This is the next phone in that line.

The Z Force has Motorola's ShatterShield technology, which means you can drop your phone on your marble floor or throw it at your assistant and it won't break. The Z Force represents all the best Droid ideas—super-thin body, unbreakable screen—and the customization of the Moto X.

The Moto Mods are the real selling point. Attach an accessory to the 16-pin port on the back of the phone and the Z becomes something new. A projector called InstaShare makes the phone huge but adds a big battery and kickstand while turning your phone into a wall-sized screen. Another, built with JBL, adds a big speaker.

It's important to note that Project Ara, Google's modular smartphone initiative, started as a Motorola project. (Remember "MAKEwithMOTO"?) Clearly, the ethos hasn't left, even it Ara did. Still, the Moto Z phones aren't quite modular the way Project Ara is. Ara phones let you swap screens, cameras, and batteries. Motorola's approach is more like what LG did with its new G5, where you plug extra modules into an already complete phone. Motorola has an easier switching mechanism, and Moto Mods is a way better name for the modules than LG's "Friends."

It's smart: many people will never use the mods, and can use the Moto Z as the wafer-thin phone that it is. Or, they can wonder about those pins and turn their phone into something cool and new.

The Moto Z arrives this summer for Verizon customers, with everyone else getting it later this year. Motorola is working with developers to build mods and imagines everything from a huge battery to a laptop dock to a virtual keyboard. Their pitch is the same as every other modular phone: Everyone needs something unique, and you should be able to have the phone you want. It's hard to argue with that.