From the email:
BAGGAGE: Excess valuation may be declared on certain types of articles. Carriers may apply special rules for fragile, valuable, or perishable articles. Check with your carrier. Checked Baggage: Carriers may permit a free checked baggage allowance, which is set by the carrier and may differ by class, and/or route. Carriers may apply extra charges for checked baggage in excess of their permitted allowance. Check with your carrier. Cabin (Unchecked) Baggage: Only ONE small item of cabin baggage per passenger will be allowed into the aircraft (subject to space availability) MAXIMUM SIZE: 17” x 11” x 9” (43cm x 28cm x 23cm) MAXIMUM WEIGHT: 11lbs (5kg). It is recommended that cabin baggage be kept to a minimum. Check with your carrier. If more than one carrier is providing the transportation for your journey, each carrier may apply different rules on baggage (both checked and cabin). SPECIAL BAGGAGE LIABILITY LIMITATIONS FOR US TRAVEL: For domestic travel wholly between US points, federal rules require any limit on a carrier’s baggage liability to be at least US$3000.00 per passenger, or the amount currently mandated by 14 CFR 254.5.
Where does it say on the website that the 5 kilos is included in the 20kilos?