There was a thread a while back, now closed discussing these.

Based on it, I bought several packs of the BCM plastic snap in type. Worked great for intermittent shooting. Last week, I was running through mags fairly rapidly, working on transitions (club match next weekend, typically run through 70-85 rounds in ~90 seconds on targets from 3 - 100 yards).

BCM plastic is nice an grippy, but does diddly for limiting heat transfer. Needed a new plan.

VZ Grips makes very nice G10 panels - but pricey. https://vzgrips.com/rifle-grips/inter-lok-rail-grips (they come in M-Lok too) Got some 4" and 2" pieces, and finished off the back of the rails with the remaining BCM. G10 is much better on heat transfer than the plastic. Added a BCM offset rail for my light while I was at it. Final product looks like:

I found that the skinny BCM covers work best on octagonal rails (like the BCM Alpha rails), where they can be applied on all sides with no gaps, to provide full coverage protection for your hand.

With rails like yours, that only have Keymod slots at the 3/6/9 o'clock positions, the wider Midwest Industries covers are nice, since they will still provide full coverage, even with only three panels applied.

So while those skinny G10 panels may work better, you might still find that there's excessive heat leaking out between the panels and into your support hand.