Spec-Wipes Spec-Wipe 4 Wipers Case. Combining top-notch and uncompromising quality with an affordable price the Spec-Wipes Spec-Wipe 4 Wipers 21912-046/ 21912-046 can fulfill your laboratory needs while still offering a great value for the money. Product Category Description: Wipers are made of 100percent double-knit polyester delivering softness high absorbency strength and abrasion resistance. Continuous-filament construction fortifies the fabric against breakdown. Textured yarn construction and clean-cut edges result in less linting and snagging. A proprietary cleaning process reduces particulates and extractable contaminants. Laundered in an ISO Class 4 (FED-STD-209E Class 10/M2.5) cleanroom. Flat packed. Specifications for Spec-Wipes Spec-Wipe 4 Wipers 21912-046 : Dimensions cm (in.): 22.9 x 22.9 (9 x 9) Unit: Pack of 150 Particle Generation (>=0.5 m) Biaxial shake (IES test method): =0.5 m) Fibers (>=100 m): 2/cm2 Extractables Using Deionized Water: