Apple CEO Tim Cook speaks at an event in San Francisco / Getty

A smaller iPhone, a new big iPad and Apple watch straps will be the headline releases at the big event

Apple is set to hold one of its big events on 21 March, showing off new products. But nobody is clear what exactly those products will be.

None of Apple’s big products – primarily the iPhone – are due for their yearly update. Instead, the company is thought to be releasing a range of smaller upgrades, with one big exception.

The biggest release will likely be the iPhone SE. That will be a smaller iPhone that will look like the iPhone 5 but bring features from newer phones, and is thought to be launched at those that want a smaller or cheaper handset.

That won’t however be the only product launched next week. Here’s our rundown of everything that’s expected to come out.

iPhone SE

A lot is already known about the phone that is expected to launch: it will look like an iPhone 5 but with rounded edges, and feature internal components that are somewhere between the iPhone 6 and 6s.

Perhaps the one big remaining question is what Apple will call the new phone, and the related puzzle of how it will sell it. The company was originally thought to be calling the iPhone 5SE, but it seems to have dropped that number – it isn’t clear how Apple will disassociate it from the iPhone 5 that it is expected to look like, or how it will look to encourage people with that phone to upgrade.

iPad Pro

Despite the different name, what Apple will really be introducing an updated version of the iPad Air.

But it will include new features from the bigger and recently introduced iPad Pro, too. That will include support for the Apple Pencil, smart connectors so that it can connect to keyboards and new speakers that will help it get the expansive sound of its bigger sibling.

For that reason, Apple is expected to name the new tablet the iPad Pro. There will then be two sizes under that name – the big tablet that was introduced late last year, and the new smaller tablet.

Apple Watch accessories

Some had thought that a whole new Apple Watch might be on its way at the March event. But Apple seems instead to be moving towards a release schedule that sees new updates come out more than once a year, and instead the event will see accessories.

Those are likely to include the black Milanese loop that accidentally appeared on the Apple Store, as well as new material, Nato-style loops for people to use.

The new Apple Watch accessories seemed to be referenced in the event invitation, which included the cryptic message: “Let us loop you in”. Though that might also be a reference to Apple’s 1 Infinite Loop address, it’s also probably a suggestion that new straps are on their way.

iOS 9.3

Apple has trailed and tested the new update for the iPhone and iPad operating system, and it’s very likely that it’ll come out ready for the new devices.

The update includes new features like a special mode to help people sleep, and new security settings.

It isn’t clear that Apple is lining the new release up for the March event, but the timing seems more than convenient and the software is due for release very soon.

One more thing?

Apple still has a knack for surprises – though more has tended to leak out from it in advance in recent years.

It’s almost certain that Apple is working on a new version of the full-sized iPhone, the iPad Mini, the Apple Watch and many of its Macs. It’s also likely that it’s working on whole new categories of products – recent rumours have included virtual reality as well as the long-rumoured Apple Car.

But there has been no suggestion in advance that anything else is on its way. And given that Apple products tend to be at least a little flagged in advance nowadays, it’s probably that those three products will be the big highlights.