套筒。本身不是完整刀座，而是把刀具或鑽夾頭轉接到機台既有孔位的過渡件，外徑配機台、內徑配刀具。
對應 Citizen 料號 SAU825。本款不使用夾頭，刀具直接夾持；最大刀柄 25.4 mm；刀座柄徑 31 mm。
Mongtec Precision 為台灣品牌，台中設計製造。
| Mongtec model | SAU825 |
|---|---|
| Machine brand | Citizen |
| Citizen reference code | SAU825 |
| Holder type | Sleeves |
| Max tool shank | 25.4 mm |
| Holder shank diameter | 31 mm |
| Collet | — (no collet; tool clamped directly) |
| Drive | Static (not driven) |
| Max speed | — |
| Brand | Mongtec Precision Inc. — Taiwanese brand, designed and engineered in Taichung, Taiwan |
| Model | Type | Max tool shank | Collet | Drive |
|---|---|---|---|---|
| GDE1025 / GDE10254 | Static drilling toolholders (internal coolant) | 19.05 mm | — | Static |
| MSC507 | Axial toolholders | 7.0 mm | ER11 | 1:1 · 10,000 rpm |
| GDF1801 | Static 4 holes drilling toolholders | 25.4 mm | — | Static |
| GDF1207 | Static 3 holes drilling toolholders | 19.05 mm | — | Static |
英文版：English version · 走心式刀座總覽 · 動力刀座 · 靜態刀塔刀座