SCHEMA:
CREATE TABLE table_26967904_1 (chambering VARCHAR, f_bolt VARCHAR, p_max___bar__ VARCHAR)
USER:
With what type of chambering is the F bolt n (lbf) and the P max (bar) 3900?

QUERY:
SELECT chambering FROM table_26967904_1 WHERE f_bolt = "N (lbf)" AND p_max___bar__ = 3900