When I started sashiko stitching, the sashiko thimble was a mystery to me!

It's an odd shaped soft leather thing that doesn't resemble any thimble I ever saw.  Then I saw an elderly woman who was sashiko stitching, and she was using one - and I had the ah ha! moment.  It is meant to sit at the base of you finger with that extending pointing in toward your palm. We carry two in our sashiko section, the leather Olympus sashiko thimble and the Clover metal sashiko thimble with plate
                              

I never have used a thimble and still don't, but I gave it a try just now, and find I can put 4 or 5 inches of stitching on my long sashiko needle at once, and if I am using the thimble to push the needle through, it is not a problem. I can't pull that many stitches through at once, so for long straight sashiko lines it would speed up the stitching quite a bit.  Plus it does take strain off your fingers.

How to:
You wear a sashiko thimble pushed to the base of your second finger as shown. I have fatter fingers than most women so I would want to loosen the knot in the elastic at the back.  For most of you, I think the width it comes in will fit comfortably. 

To use the thimble gather your stitches on your needle, rest the end of the needle against the thimble and push.

Huh! I just noticed I have it on the wrong finger in this photo! Take a look at the package image above- they show it on the finger next to the index finger!