Check the listing for details. Quadratic Acoustic Diffuser panel qrd Sound diffusion sonic studio treatment. Color: natural, Condition: New. Listed at 139.99 USD. These are solid wood 7 well QRD diffusers, Handmade in my shop here in rural Indiana. The over all dimensions are 46 x 13 1/4 x 3 3/8 inches, the maximum well depth is 3.125 inches, and each well is 1.5 inches wide. Weight is around 24 lbs. These are designed to diffuse frequencies from 1300hz to 4500 hz (and may scatter frequencies as low as 650 hz). minimum distance to seating position is about 34 inches These are a useful tool in your arsenal for acoustic treatment. They can help a small room feel larger and tame flutter echos without killing all the natural ambience in the room. these can be mounted to the wall (no mounting hardware is included, but they can be screwed directly to the wall) or can be used as a free standing unit I designed these to be as economical as possible, they come in natural unfinished wood, and you can use them as they are, or apply your own stain and finish. I call them "the working mans diffuser" they aren't as polished as some, but they come in at a fraction of the cost of most other qrd diffusers in hopes of making them more accessible to the average musician. These are made to order, and will typically ship within 2 weeks.