Check the listing for details. Primacoustic Cumulus Tri-corner Bass Trap - Gray (2-pack). Color: Gray, Condition: New. Listed at 204.99 USD. Clean Up Your Studio’s Low End Gaining control of low-end frequencies is one of the most important things you need to consider when building a studio. Failure to do so is a surefire path to inaccurate monitoring and, consequently, subpar mixes. Made from high-density glass wool, Primacoustic’s Cumulus offers an easy, cost-effective solution to that age-old problem. This tri-corner bass trap captures low-frequency sound as it migrates to the corners of your room, effectively attenuating frequencies 100Hz and up. Its unobtrusive design looks great in any room, and thanks to its Class A/1 fire rating, it’s safe to use anywhere. To top it off, Cumulus bass traps are a breeze to install, by virtue of their unique spring-tensioned clamping system.