This is a Bussmann KTK-R-7 fuse—7 amp, 600 volts AC, fast acting, and it's a Class CC fuse.
That means it's built for industrial control panels, motor circuits, transformers, that kind of stuff.
It's the little glass tube-looking one, but don't let the size fool you—it's rated for serious voltage and interrupts faults fast to protect sensitive equipment.

Dimensions are 13/32 inch by 1-1/2 inch, so it's the standard size for these Class CC fuses.

It's brand new, still in the packaging.

No MPN listed, but it's a genuine Bussmann, which is a name you can trust for electrical components.

If you're replacing a blown fuse in a panel or just keeping spares on hand, this is the right one.

Fast acting means it blows quickly on overcurrent, so it's good for protecting things like drives or controllers that don't tolerate surges.
If your application calls for a KTK-R-7, grab this and get back up and running.