DANGER CONFINED SPACE ENTER BY PERMIT ONLY - Confined space sign alerts that entry can only be made when authorized by permit only. Restrict entrances to confined spaces by posting in entryways. Confined space sign is perfect for alerting workers of conditions and restrictions. Traditional OSHA-style signs, tags and labels are the most widely recognized design format in the industry. Danger header indicates a hazardous situation that, if not avoided, will result in death or serious injury.