Helvetica MH1.L2210.LG watch strap.
It is possible to fit this strap yourself, it is a little fiddly but relatively easy. Check out this video.
Having trouble finding your strap? More help is here
Helvetica MH1.L2210.LG watch strap. 18mm Tan leather stitched strap.
Helvetica No 1 Light 38mm diameter.
Some watches come in different sizes, so please check the width of your strap and/or the diameter of your watch.