It is used for centering casing strings and preventing damage to filters during their descent into the well.
| Nominal pipe diameter, in | 4,02 | 4,49 | 5 | 5,75 | 6,61 | 7,01 | 9,65 |
| Outer diameter at the blades, in | 4,92…5,63 | 5,12…5,87 | 5,91…6,42 | 6,50…8,46 | 7,28…8,82 | 7,76…8,82 | 10,83…12,71 |
| Length, max, in | 7,87 | 7,87 | 7,87 | 11,81 | 11,81 | 11,81 | 12,2 |
| Inner diameter (+0,08), in | 4,09 | 4,57 | 5,08 | 5,87 | 6,73 | 7,13 | 9,76 |
| Body diameter (±0,04), in | 4,72 | 4,92 | 5,71 | 6,3 | 7,09 | 7,56 | 10,51 |
| Blade width, in | 1,18 | 1,18 | 1,18 | 1,57 | 1,57 | 1,57 | 1,97 |
| Screw hole size | М10 | М10 | М10 | М16 | М16 | М16 | М16 |