6" x 10" Cast Aluminum Manhole is ideal for heavy duty applications. It surpasses AASHTO M-306 traffic rating. The low profile design makes it ideal for sampling indoors. SpecificationsMaterial: Aluminum Alloy Curb BoxLid Style: Single Bolt Expansion LidOuter Diameter: 6-7/8"Inner Diameter: 5-3/4" Clear HoleSkirt: .25" Wall Thickness, AluminumRating: AASHTO H20, AASHTO M-306, Traffic ratedWheel Load Capacity: 40,000 lb Meets the following load requirementsAASHTO H-20 Traffic RatingAASHTO HS-20 Traffic RatingAASHTO M-306 Traffic Rating