T-Mobile is holding a sweepstakes for chances to "preview" the upcoming LG G4 and winners won't have to return the handsets after getting their hands on them.

LG hasn't committed to a release date for the G4, but T-Mobile has announced that the smartphone will be available in its lineup for the spring quarter.

T-Mobile wants consumer feedback on LG's latest flagship phone, so it is holding the sweepstakes for the G4. Those who register here by May 25 will have the chance to provide T-Mobile with that feedback and keep the phones.

"T-Mobile is the only wireless provider where customers can sign up for the chance to get their hands on the LG G4 superphone BEFORE it's available for purchase in the US," says T-Mobile. "The Un-carrier is launching a sweepstakes and exclusive preview program with LG to find out what its customers think of the new T-Mobile LG G4."

The G4, expected to sell for about $650 in the US, launches today in South Korea and will arrive in other countries in May and June.

The 5.5 inch display returns in the G4, though the new flagship is about 25 percent brighter and outputs about a 20 percent wider range of colors. The IPS Quantum Display is also more energy efficient than the G3's screen.

A six-core Qualcomm Snapdragon 808 powers the G4 and is tuned to deliver optimal performance for the handset's imaging and display elements, including the camera. The G4 has a hefty 3GB of RAM and 32GB of long-term storage.

The G4 sports a sharp set of cameras, boasting a 16MP shooter on its back and an 8MP selfie cam on its face. The pair is a significant step up from the G3's 13MP rear and 2.1 front camera.

Coating a base of Android 5.1 Lollipop, LG's UX 4.0 will give the G4 a unique flavor. But the user-interface wrapper isn't designed to change the Lollipop experience too extensively.

The G4 will come in metallic gray in the US and a brown leather-back version will be carried exclusively by T-Mobile in the States -- there are a total of six different leather-back versions of the phone. Along with the G4, T-Mobile will also add the LG G Stylo phablet and mid-tier LG Leon in the spring quarter.

Check out T-Mobile's demo of the LG G4 in the video shown: