Hi Vilma,
We're glad to help! The Stainless Steel Drip Tip for 510/901/KR808 will work great with the Aspire Nautilus Mini, and it's just 19mm in length.
http://www.smoktek.com/Stainless-Steel-Drip-Tip-for-510901KR808_p_226.html
Best regards,
Brad