Heatsink is out of stock

[EasternPA]

Here is a 4-pack of another heatsink that looks identical to the untrained eye.

https://www.amazon.com/100x60x10mm-Aluminum-Amplifier-Transistor-Semiconductor/dp/B07PJYDCMH

[ErichMoraga]

They're also extremely plentiful in eBay.