Sewing Machine Needles – These needles are used on industrial sized sewing machines such as  Consew, Juki, Pfaff and more. Available in three thicknesses. 135 x 17 Regular thickness for upholstery fabrics and a thinner gauge for sewing leather vinyl and canvas materials (makes smaller holes). The last two digits in the numbers indicate the thickness of the needle. 23 gauge being the thickest.  23 – Thickest  337 338 624 20 -Medium 339 340 625 18 – Thinnest 1715 1716 1717