Butt joint tool by Trim-Tex Inc.
The EZ-Backer splicer allows one to get a perfectly strong, flat finish of seams between joists by attaching only to drywall. The tool pulls back the edges of cut ends of wallboard creating a tapered area. Edges can then be finished as a standard tapered joint resulting in a flat wall. The splicer installs with drywall screws; the tapered edge becomes permanent and will not release or cause seam cracks.