The best replacement for plenum is pvc.

The best alternatives to plenum are rated as following:
★★★★★  pvc
★★★★★  riser
★★★  non plenum
★★  non plenum cable
★★  riser cable
★★  non-plenum
★  duct
★  ducted return
★  pvc cable
★  riser cat6
★  lszh
★  intake manifold
★  dsb
★  riser fiber
★  shielded
★  utp
  riser rated
  cmr
  plenum
  no plenum
  spacer
  in wall rated
  low smoke
  pvc cat5
  non-plenum cable
  riser rated cable
  cl2
  pvc cables
  lsoh
  riser cat 5
  cat 5e riser

Your alternative for plenum is not listed? Suggest!
Speaking about plenum, one probably shouldn't forget about itbs.

Other search terms related to plenum and their ratings are:
★★★★★ itbs
You have in mind a companion for plenum and it is not yet here? Propose!



Google Trends

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plenum
pvc
riser