DISCONTINUED Scan Speak 29001 Flow Resistance Vent

I'm using these in box that was originally for a sealed woofer configuration which is the intention. The box is about 60% stuffed with a fiberglass tunnel behind the 8" woofer that's open to the vent. After dissatisfying performance from the original and another sealed parameter woofer, I installed a vented parameter woofer I had used in a retired t-line. Wow, deep, tight powerful t-line like performance without the complications, as many have described aperiodic enclosures. Serendipity rules. It's a shame they're discontinued because of the potential when successfully used.

installed in a 1.26 cu' enclosed box with a 12' alpine sub and seemed to produce a flappy sound; however, when i covered this vent with duct tape the flappy sound diminished.

have not used it yet due to undersized sub box sounding great with out it, looks simple enough to replicate