Retailers have reduced the inventory of iPhone 5s and older models of iPad in anticipation of the next-generation 4-inch iPhone 5se and smaller iPad Pro.

Apple launched the iPad Pro as well as the iPhone 6s and the iPhone 6s Plus at an event in September 2015. The successor of the iPad Air 2 and iPhone 5c missed the party. However, rumors suggest that Apple will launch the iPad Air 3, also dubbed smaller iPad Pro, and the iPhone 5se at an unannounced event on March 22.

Even though Apple has not confirmed the launch date of its iDevices in March, retailers are taking steps to limit the inventory of the older 4-inch iPhones and older 9.7-inch iPads.

On Verizon's website, only the gold version of the 32 GB iPhone 5s is available. Customers who want the silver or Space Gray models of the smartphone get "out of stock but coming soon" message.

Best Buy has been selling the iPhone 5s on Sprint and Verizon for $1 on a two-year contract. However, the status of the mobile phone on the retailer's website shows "sold out online."

Reports also suggest that availability of the iPhone 5s at other retailers such as Walmart, AT&T, Target and more are also running low.

Amazon has already listed a few cases of the iPhone 5se on its website, which suggests that Apple will launch the new handset sooner than later.

Previous reports suggest that the iPhone 5se, also known as the iPhone 6c, will include an A9 processor - the same used in the iPhone 6s and the iPhone 6s Plus. Speculations are also rife that the upcoming pocket-friendly iPhone will have Apple's fingerprint sensing technology called Touch ID, which will allow for easy unlocking of the device and for making online payments.

The iPhone 5c included a polycarbonate body, which gave a plastic look to the smartphone. However, the iPhone 5se may have a metal frame that will give a premium feel to the device. The upcoming iPhone may cost between $400 and $500.

Apple Insider's price guide also shows the iPad Air being sold out or on backorder, which means that many retailers are not replenishing their stock for older iPads.

The 9.7-inch iPads are one of the most popular iPads available in the market and customers who were waiting for a new version of the iPad in 2015 were left disappointed. However, tablet fans can expect Apple to launch the smaller iPad Pro in March with enhanced features and support for Smart Keyboard and the Apple Pencil.