811A die head: threading machine dies head:Fits Model 300 300A, 500, 500A, 535, 535A, 800, 801, 802 1822 Machines Item: 12R diehead1. 12R pipe threading die head comes with one set of NPT dies2. 1/2 manual threading die head has a right hand thread direction.3. Exact replacement for part number 373904. Lifetime Guarantee against manufacturing defects.