Everything we expect at Apple's iPhone event on March 21 - CNET

"The bigger announcements, particularly the redesigned iPhone 7, are expected to come in the September event," said Piper Jaffray analyst Gene Munster.

Apple declined to comment.

What we expect

A new 4-inch iPhone

Apple made waves in 2014 when it introduced its 4.7-inch iPhone 6 and 5.5-inch iPhone 6 Plus, a move that helped it regain its edge against Samsung's Galaxy devices and other jumbo-sized Android phones.

But iPhone sales are slowing down, and there are still a lot of users who haven't upgraded their devices in years. More than half of the iPhones used in the US are the 2-year-old models or older, according to Kantar WorldPanel.

Enter the smaller iPhone SE (or 5SE?), which probably will look a lot like the 5S on the outside but with the guts of an iPhone 6 or 6S. It likely will support the Apple Pay mobile payments service but not some of the iPhone 6S's features like 3D Touch, which lets the display respond to different levels of pressure.

The most anticipated feature of the new iPhone, though, is its pricing. Some analysts are hoping for a $350 price tag for the iPhone SE. UBS analyst Steve Milunovich, though, estimates that even if the new iPhone SE costs $450 -- the same price as the iPhone 5S currently -- it would be good enough for people with the older iPhones to upgrade.

Updated 9.7-inch iPad

Apple released its hulking 12.9-inch iPad Pro and the petite 7.9-inch iPad Mini 4 last fall. On Monday it will introduce a follow-up to its iPad Air 2.

Look for additions similar to what we've seen in the iPad Pro, including Apple's Smart Connector technology that supports an Apple-designed keyboard cover and an Apple Pencil stylus.

Will a new iPad Air get people excited about tablets again? iPad sales have been in freefall for the past two years. Apple hoped November's iPad Pro would buoy sales by attracting business users, but it hasn't caught on. In the December quarter, unit sales tumbled 25 percent to 16.1 million. That marked the eighth quarter in a row iPad sales have fallen from the previous year.

New Apple Watch bands or software

Apple's tagline for Monday's event is "Let us loop you in." That could be nod to Apple's headquarters at 1 Infinite Loop, but it could also be a hint about new Watch bands. We could see new colors and materials, as well as partnerships like those with fashion brand Hermes.

The company also may update watchOS, the software running on Apple Watches. New features could include being able to use many watches with one iPhone and improvements to Apple Maps.

Apple may use the event to introduce the iOS 9.3 mobile software, which has a feature called Night Shift that changes the display to make it "easier on your eyes" before you go to bed.

Security talk

Apple's product launch comes a day before it faces off with the FBI in a Riverside, Califoia, court. Apple and the US govement have been battling for weeks over the extent to which the company should help pull data from an iPhone used by one of the shooters in December's San Beardino, Califoia, massacre.

CEO Tim Cook should spend a small part of Monday's event talking about Apple's position.

"I don't think they'll dwell on it much," Kantar Worldpanel analyst Carolina Milanesi said. But not discussing it, she said, would be "ignoring the elephant in the room."

Likely no-shows

Apple Watch 2

Apple released its first smartwatch a year ago, which means it's time for Apple Watch 2.0. Right? Wrong. We're not expecting the company to introduce its second smartwatch at this event.

iPhone 7

This is such a long shot, it's barely worth mentioning.