These little mid woofers were made for Stewart Film Screen as part of on wall speaker systems for their screens.  They feature polypropylene cones with rubbers edges.

• 5.25" dia.
• 8 ohm
• 4-1/8" cut out
• 2-1/4" dept
• fs 69Hz
• Qts .49
• Vas 4.2L
• Spl 85.2 dB