Tuffbond® 394 is a single component, high temperature resistant, heat activated epoxy. It cures to a high-performance thermoset system with excellent adhesion properties to a wide variety of substrates. Tuffbond® 394 will change from amber-yellow to a reddish brown upon cure. Bonding the voice coil to the cone has been a challenge for engineers, specifically when the adhesive temperature resistance requirement is above 200°F (93°C). Two component epoxy was commonly used for this application, but limitations such as mixing ratio, cure speed, potential solidification in equipment and the need for equipment flushing solvents have made Tuffbond® 394 more practical.