Cannula HolderFeatures The Cannula Holder was designed to hold 3. 4 mm cannula heads, as manufactured by Plastics One for cannula sets, and DURECT for ALZET Osmotic Pumps. Non intrusive for cementing cannulas in place. Options Order code Product name Description 505253 Cannula and Minipump Holder The 505253 holds the cannula vertically directly in line with the shaft of the probe holder. 505254 Cannula Holder The 505254 holdes the cannula away from the shaft of the