Rotary Corp brand aftermarket product. T-Wrench 19mm x 13mm with T-27 Torx Bit. Replaces Chainsaws 19mm x 13mm (3/4" x 1/2") 3" Barrel with a 7-3/4" long handle. Replaces Replaces 4128 890 3400, 4224 890 3400. Dolmar 940 827 000, 506 38 26-01, Makita 940 827 000 & Partner 506 38 26-01.