The D R1 R2 - d - λ1/λ2 from Meadowlark Optics, Inc. is a Waveplate with Wavelength Range 488 to 1064 nm, Waveplate Thickness 0.14 to 0.27 Inch(3.6 to 6.9 mm), 3.6 to 6.9 mm, Waveplate Diameter(Inch) 0.5 to 1 Inch, Waveplate Diameter(mm) 12.7 to 25.4 mm. More details for D R1 R2 - d - λ1/λ2 can be seen below.