New 08 BTL, Induct heat ring?

[Travo-18 1]

I'm buying 2 BTL 15's today and I just want to know what this option is? And what its purpose is.

Thanks

[muddybass 13]

Just an aluminum shortening ring on the inside to help cooling a little bit more...

[Travo-18 1]

Ah I see thanks man!

[Fi Car Audio 64]

Its a machined aluminum ring in the gap that lowers the voicecoils inductance (allowing it to play up higher and have a little better overall transient response). It also reduces the volume inside the magnet gap of the motor increasing air speed with the cooling as well as allowing the coil to kick off heat to a more receptive thermal mass than magnets...

Thanks,

Scott