Help me ID and replace a frame slider

[Johnson]

Noticed one of the "caps" on my frame slider is missing. I am the third owner so have no idea what these are. Tried searching on Ebay but no luck. I have 2 pics, one with the blue cover and one without. Where can I order the cover for the other one. Excuse picture quality, dropped my phone and things haven't been the same...

https://i.imgur.com/coj83md.jpg

https://i.imgur.com/RvceJDl.jpg

 

[VEGASRIDER]

Picture quality is poor, but it might be called Uncaged. I have a set on my bike, they work well. Unfortunately they aren't around anymore and if you really needed to get a set of new caps, you would have to find a machine shop and get them made.

 

[MIJ_FZ6]

Are those made out of metal? If so you should really ditch them, high chance it will crack the frame on the bike if it falls.