CREATE TABLE table_29164 ("Chambering" TEXT, "P1 diameter  ( mm ) " TEXT, "A external  ( cm 2  ) " TEXT, "P max  (  bar  ) " FLOAT, "F bolt  (  kgf  ) " FLOAT, "F bolt" TEXT)

With what type of chambering is the F bolt n (lbf) and the P max (bar) 3900?
SELECT "Chambering" FROM table_29164 WHERE "F bolt" = 'N (lbf)' AND "P max ( bar )" = '3900'
SELECT "Chambering" FROM "table_29164" WHERE "F bolt" = 'N (lbf)' AND "P max ( bar )" = '3900'