Marine M Speaker Technologies Reviews
Marine Speakers: Size Information
M770 Series Oversized 7.7-inch Speakers   Woofer Frame Outer Diameter (A):  7.70 in. / 196 mm Bolt Hole Circle (B):  6.92 in. / 176 mm Woofer Mounting Hole Diameter:  6.25 in. / 159 mm Woofer Mounting Depth:  3.15 in. / 80 mm   Oversize design results in more cone area, higher output and better bass response than "6.5-inch" marine speakers. Requires larger mounting hole and mounting flange area.	M650 Series Narrow-Flange 6.5-inch Speakers    Woofer Frame Outer Diameter (A):  6.55 in. / 166 mm Bolt Hole Circle (B):  5.79 in. / 147 mm Woofer Mounting Hole Diameter:   5.00-5.25 in. / 127-133 mm Woofer Mounting Depth:  2.95 in. / 75 mm   To allow fitment in tighter spaces, this speaker has a narrower flange and a smaller bolt hole circle than a standard marine "6.5-inch" speaker.
MX650 Series Standard Flange "6.5-inch" Speakers Woofer Frame Outer Diameter (A): 6.90 in. / 175 mm Bolt Hole Circle (B): 6.125 in. / 155.5 mm Woofer Mounting Hole Diameter: 5.00-5.25 in. / 127-133 mm Woofer Mounting Depth: 2.74 in. / 69.5 mm This speaker uses a standard, wide-flange ,marine 6.5-inch, frame (which is actually 6.9-inches in diameter) and is a direct replacement for most marine -6.5-inch speakers.