that looks like an aluminum cone??? they are often used in Hartke Bass guitar amplifiers. MCM electronics also sells some. if theya re aluminum, they are not good for home audio. or even pro audio. but for a bass guitar where you want a colored resonant sound they are ok. some people like the very bright tone they give.
No markings on the back? Those mostly can lead us to what it is. The front alone is to generic to know.
