In a conversion sleeve comprising a large diameter part, a small diameter part, and a tapered diameter part interconnecting said two parts, a ferrule insertion stop part is formed on an inner circumferential surface of the tapered diameter part and/or inner circumferential surfaces of the large diameter...http://www.google.fr/patents/US6872008?utm_source=gb-gplus-shareBrevet US6872008 - Conversion sleeve and optical adapter
