that is the cts speaker that used to come in b-15's in the mid to late 60's. yours is from 1967. sounds great in old b-15 cabs...i've got one in mine. but won't handle much wattage. if it does 100w, i'd be surprised.
The old Chicago telephone systems square magnet jobby is a great sounding speaker, as jimmy says not fantastic power handling but great smooth upper mid response and good efficiency.
Records very very well.
+1 
