Virtual Machine (VM) bursting is now generally available on more VM types

Virtual Machine (VM) bursting is now available for the following virtual machines: Dsv4, Dasv4, Ddsv4, Esv4, Easv4, Edsv4, Fsv2 and B-series virtual machines. VM bursting enables customers’ workloads to handle unforeseen disk traffic spikes smoothly without the need to overprovision their virtual machine.
Source: Azure Roadmap