Fig. 1

a. Catheter introducers（ catheter inserters） make it easy to introduce a catheter with a strong shape, fragile tip, or balloon, by protecting these features.

b. Loading a catheter introducer from the catheter tip after strong shaping is difficult.

c-h. Various catheter introducers. Packaged（ c） is provided separately whereas（ d-h） are adjunctive parts of a catheter set;（ c-f） are for microcatheters while（ g） and （h） are for balloon guiding catheters;（ d-f） are slit type introducers（, c）（, g）, and（ h） are split type introducers.