C.R. LAURENCE PL16138 CRL Black Adjustable Screen Frame Corner - 20/PK. CRL Adjustable Screen Frame Corners are riveted together to allow the two legs to swivel. Ideal for making hex or octagonal screens, or for attaching radius top screens to rectangular bottoms. These plastic corners fit 3/4" x 7/16" (19 x 11.1 mm) CRLWSF347 and A347 miter cut Screen Frame.. Part Numbers Variations: PL16138