user: Question: what are all the barrel lengths whith the name  AR-15A3 Competition HBAR
Columns: ['Colt model no.', 'Name', 'Stock', 'Fire control', 'Rear sight', 'Forward assist', 'Case deflector', 'Barrel length', 'Barrel profile', 'Barrel twist', 'Hand guards', 'Bayonet Lug', 'Muzzle device']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['R6000', 'AR-15 Sporter (SP1)', 'A1', 'S-1', 'A1', 'No', 'No', '20 in.', 'A1', '1:12', 'Triangular', 'Yes', 'Type 2 Duckbill or A1']
SQL:

assistant: SELECT "Barrel length" FROM "Table" WHERE "Name" = 'AR-15A3 Competition HBAR';