Dimensions: 
Each quartered hull =
6 in. wide x 8.75 in. long x 1 in. deep.

The inner-rim clamping surface =
I in. wide x 1/4 in. deep

Accommodates a typical 6" to 8" architectural in-wall speaker.

Installation:
Sand-fill each quartered hull via the sand fill-hole.
Use clean dry sand. Avoid beach sand.

Trim a funnel to sit on the inner-ledge of the sand-fill hole.
This minimizes insertion depth which provides easier flow.

Available at local parts stores & amazon. 

Stand the SandTrap near vertical.
Then scoop and shake to fill a pair in about 10 minutes.
Seal hole with glue & supplied plug.

Insert each quartered sand-fillled hull through the custom speaker cut-out.
Use an adhesive such as 3M Strip Calk to hold in place.
Poster putty is sufficient for the in-ceiling model. 
Insert and clamp the speaker to the SandTrap inner-clamp-rim. 

We have provided a "string hole" in each hull. 
Insert string or fishing line through the hole.
This allows the retrieval of a hull accidentally dropped in the wall.