With your membership you get the standard 8-1/2 x 11" Certificate shown in the small picture in the upper-right corner.  There is a 16x20" version available that is more detailed.  Below is one framed by a member and he included other items in the mat windows.  It is suggested that UV protection glass be used to prevent fading.... especially the signatures.  That increases the framing cost, but many think it is worth it.  The UV glass in this framing cost about $25 at Hobby Lobby in 2018.  The owner had access to a mat-cutting kit, so produced it for minimal cost.  He got an oversized frame at a Thrift Store and cut it down.  And the gold and blue mats were $10 or so each at HL.  For certificate ordering details, see the GSSR web site.