Scanspeak 18W/8542-00 Midwoofer - Classic Range - Proac Studio 100.
Classic Bass / Midrange drive unit. Proac Studio 100.
This popular 6.5" bass / midrange speaker has been used in various mainstream designs ~ a long term favourite with the DIY speaker building community and widely regarded as one of the finest pulp based drive units ever produced.
Features include an air dried composite fibre cone, symmetric drive and an alloy chassis.
A full datasheet can be downloaded from the bottom of this page.