This pencil-style thread tension gauge is used to set the proper top thread tension.
The top layer's thread tension gauge has a hook and slide guide on one side and is used to set the tension of the top layer's thread on commercial embroidery machines.
The slider needle works in conjunction with a spring to indicate if the tension on the top thread needs to be adjusted or relaxed.
Top thread tensions may vary up or down by as much as 5 to 10 gf. Rayon #40: 150gf,Polyneon #40: 170gf,Metallic #40-50: 170gf,Polyester CR #40: 125gf,Burmilana #12: 190gf