I did a search and came up blank. Someone replaced the phillips head [OEM] bolt on one of my tuners with a slotted, these bolts have a "dull [not shiny] finish". Best pace to find a replacement? My fallback is ACE, Home Depot etc
I believe those are 12-24 x 3/8" Phillips Round Head Machine Screws. That's the official name of what you are looking for. They may be available at your local hardware store, it's a common size. The machine screws at the hardware store are zinc plated, which is that satin-dull silver. However, you can buff them up and they will look almost like they are chrome or nickel plated.