A foam gun having a spool valve (65) with a product passage (67) received in a housing (16) shaped to accommodate the spool valve (65). The housing (16) having an outlet passage (46) and inlet passage (69) and a thin sidewall portion (61) surrounding part of the spool valve (65). A stub cylinder (118) having an opening and stub cylinder portions (122) is integrally formed with the thin sidewall portion (61). A cylindrical force-applying fitting (110) is provided having a through bore (116) matching the opening in the stub cylinder (118) and having a radial flange (112) engaging the stub cylinder (118). The radial flange (112) of the fitting (110) is urged into a compressive position with the stub cylinder (118) by a hose portion (86) and held in place by a set screw (92). A sufficient compressive force is applied to the stub cylinder (118) to distort the stub cylinder portions (122) into contact with the spool valve (65) to form a seal between the thin sidewall portion (61) and the spool valve (65).