Sapim Laser 'J' bend silver spokes  in packs of 12 spokes. Made in Belgium from high grade stainless steel. Double butted with 2.0mm diameter ends for strength and 1.5mm diameter centre section for lightness. Supplied with Sapim 12mm brass nipples.

Full details on Sapim website: https://www.sapim.be/spokes/butted/laser 

Sapim says:

The Laser is a lightweight spoke. The thin middle section of 1,5 mm needs special care while building up the wheel. You may have to use pliers to hold the spoke to prevent the spokes from winding up. Only experienced wheel builders should mount up wheels with this spoke.

Technical specs

Diameter: 2.0 - 1.5 - 2.0
Length: 145-310 mm
Weight: 283 g (64 x 260 mm)
Strength on middle section: 1500 N/mm2