Catalog says 24mm. Of course, that could have changed, like the product number......



2157 Apollo II Saturn V Scale 1/100th
Length: 43.25 in (110 cm)
Diameter: 3.94 in (100 mm)
Estimated Weight: 11 oz (311.8 g)
Fins: Plastic
Recovery: 3 Parachutes
Projected Altitude: 150 ft (46 m)
Recommended Engines: E12-4* (first
launch), Composite E30-4*
Requires 3/16 in (5 mm) Maxi™ launch
rod (2244), sold separately.

__________________
-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430