THTEN AF-100 Trimmer Blades Head Replacement Spool 30Ft 0.065" Compatible with Black & Decker GH600,GH610,GH900,GH912,ST6600,ST7000,ST7700,NST1118,NST2118,LST220,LST300 Line String Trimmer 20 Pack DF-065 Trimmer Blade the surface is smooth square

the surface is smooth square strip

537185801 Bump Knob compatible with Husqvarna T35 Trimmer Heads 537338701 537185801(2003-05)

LST420 Type 1

more durable

THTEN AF-100 Trimmer Blades Head Replacement Spool 30Ft 0.065" Compatible with Black & Decker GH600,GH610,GH900,GH912,ST6600,ST7000,ST7700,NST1118,NST2118,LST220,LST300 Line String Trimmer 20 Pack DF-065 Trimmer Blade the surface is smooth squareCompatible with Black and Decker models: GH400, GH500, GH600, GH610, GH900, GH912, ST6600, ST7000, ST7700, CST1000, CST1200, CST2000, MTC220, MTE912, NST2018, NST1118, NST2118, LST220, LST300, LST400, LST420, LST136,easy to choose the right spool for your trimmer. Easy Installation: simply push this trimmer head into the string socket and it automatically locks in place with assistance from the side push buttons For Best Use: avoid using this