Best viewed in "landscape" mode.
Butyl surround upgrade
When replacing surounds or completely rebuilding woofers (and, to some extent, midranges), a butyl rubber surround may be used.
In some cases, this is because that is the way the original part was built, in others I suggest it or the customer requests it.
Availability is dependent on whether or not I have or can get an appropriate surround for the driver in question.
There are several reasons for doing this as an upgrade. One is that butyl rubber is a more durable material than the foam used on many speakers. Another is that the material is far more immune ot air leakage (even when new, foam is a bit porous).
7 Kelsey Road, Lee, New Hampshire 03861