Resists heavy sanding, no "fuzzing", uniformly accepts paint and texture, will not "alligator" or wrinkle. 1/2" flaps act as a "lockdown mechanism" to eliminate edge cracking. Fast flex product is the only flex product at can be installed with a "automated taping tool". Creates crisp sharp lines and perfect inside angles of any degree every time. Joint tape paper backing has unsurpassed bonding to joint compound. Uniform structural bonding with corner prevents cracks and callbacks, corners will not dent, will not separate from wall and can withstand significant shifting due to settling, lumber drying and temperature and humidity variations. High strength tapered copolymer core with memory free adjustable hinge. Applications: poor framing,shrinking lumber, inside off angles and inside and outside 90-degree corners.