Most higher end stringing machines these days are with the fixed clamps that swivel and slide go up & down. Still this is a 2-action tensioning for each string. Glide bar machines are 1-action tensioning. Also, the clamps on the glide bar machines tend to be all metal and will last a lifetime whereas the clamps that swivel and go up & down tend to be plastic with metal coated teeth. So why are glide bar machines going away?