Replacing the grips around the gear selector. Are they universal and/or how do i search and choose replacements?

Hi all, I'm just after some advice from the community on selecting replacements for a worn component on my bike.

I've got a Trek road bike and the rubber grips around the gear selectors are beginning to perish. They feel sticky and have begun to wear away. I want to replace them, but don't know what to search for.

Are they specific to this model of Trek bike, to the Shimano gear selector model or are they universal? What do I need to search for to replace them and if they're universal, are there any parameters on length or thickness i need to be aware of?

I've tried a Google but am not finding enough to give me confidence on making the selection.

Here's a couple of images of the worn gear selector boots I'm talking about. The selectors are Shimano 105s: https://imgur.com/a/3RDp9mJ