Google today introduced a tool to transfer large amounts of on-premises data to Google Cloud Platform. It’s a box.

Yes, the new tool is a physical box. It’s called Transfer Appliance, and enterprise customers ship it — with their encrypted data inside — to Google, where it will be uploaded to the public cloud.

As product manager Ben Chong writes in a Google Cloud Platform blog post, “Sometimes the best way to move data is to ship it on physical media.”

Customers set up the rackable, high-capacity storage server in their data centers. The appliance holds up to 1-petabyte of compressed data.

Amazon Web Services (AWS) already offers a similar by-mail service for huge data uploads via a physical box called Snowball.

It certainly sounds like a very retro approach to cloud computing. But both web services providers say sending massive amounts of data by mail is faster than trying to upload it the cloud with a typical network.

Most enterprises have many petabytes of data, and available network bandwidth between 100 Mb/s and 1 Gb/s, Google says. This means transferring 10 PB of that data would take between three and 34 years, depending on the available bandwidth.

“In a matter of weeks, you can have a petabyte of your data accessible in Google Cloud Storage, without consuming a single bit of precious outbound network bandwidth,” he writes in the blog. “Simply put, Transfer Appliance is the fastest way to move large amounts of data into GCP.”

It’s initially available in the U.S. and comes in two configurations: 100 terabytes or 480 TB of raw storage capacity, or up to 200 TB or 1 PB compressed.

AWS’ Snowball and now Google’s Transfer Appliance also showcases the stark difference between the two service providers’ cloud strategy compared to that of Microsoft, Oracle, and IBM. The three latter companies believe enterprises will always want to keep some workloads on premises while moving others to the public cloud. To this end, they are investing in products and services that will make corporations’ hybrid cloud ecosystem as seamless as possible.

Case in point: the Microsoft Azure Stack, which lets enterprises build a private-cloud version of the Azure public cloud in their own data centers.

AWS and Google, however, have taken a different approach that aims to make it easier for companies to migrate all of their workloads to the public cloud. Let’s hope the data isn’t lost in the mail.