The 53.01.389 main spindle clamping finger sleeve is a precision mechanical component designed for the Gildemeister DMG Mori GM16AC multi-spindle lathe, used in the bar clamping system with Q0001870 bar clamping collet for machining bars up to 16mm maximum diameter. The main function of the sleeve is to take rotation from the main spindle and act as the operating support for clamping fingers 5301387 and ring 5301382, components that through their mechanical action push ring 5301384 and bell 0801351, generating the pullback movement required to close the collet on the bar. In this configuration, the sleeve is not merely a housing body but a kinematic element connecting main spindle rotation with the bar closing control system, maintaining motion continuity, correct position of the thrust elements and controlled transmission of loads between clamping fingers, rings, bell and collet. During the working cycle, rotation from the main spindle is transferred to the sleeve; clamping fingers 5301387 and ring 5301382 housed in the component act as command and thrust elements, while their action on ring 5301384 and bell 0801351 produces the pullback of the clamping chain, allowing collet Q0001870 to close stably on the bar. This sequence requires precise seats, intact sliding surfaces, correct guidance of the key and absence of abnormal play, because any wear in the keyway or sliding areas can change stroke regularity, alter load distribution and reduce clamping repeatability. Even in the variant for bars up to 16mm diameter, where the machined sections are smaller than on larger models, stability of the closing kinematics is essential to prevent micro movements, vibration, slipping, loss of concentricity, cutting instability, dimensional errors, form errors and workpiece geometry defects. From a kinematic point of view, sleeve 5301389 participates in several machine functions: it receives and follows main spindle rotation, houses and positions clamping fingers 5301387, integrates ring 5301382 into the command sequence, enables thrust transmission toward ring 5301384 and bell 0801351, generates the pullback movement required for closure of collet Q0001870 and keeps the bar clamping group behavior coordinated with the spindle drum, bar feeding system, main spindles, possible front tool spindles, radial slides, axial slides and auxiliary machine systems. Correctly controlled bar gripping allows subsequent machining stations to work on a stable and well positioned workpiece, improving dimensional repeatability, surface quality, geometry control and production continuity. Over time, the sleeve may wear significantly in the keyway seat, which is a sliding and functional locating area; wear may cause increased play, loss of guidance, irregular movement, poor phase accuracy between command elements and deterioration of force transmission. For this reason, the part must be inspected during replacement of clamping fingers, checking the condition of the keyway seat, support surfaces, contact areas and parts subject to compression and rubbing. If wear marks, steps, ovalization, deep impressions, deformation or abnormal play are found, replacement of the sleeve becomes a recommended technical intervention to restore the correct pullback kinematics and full efficiency of collet closure. For preventive and extraordinary maintenance departments, machine tool builders, automatic turning shops, automotive production and precision engineering, the 53.01.389 clamping finger sleeve is a critical spare part for maintaining reliability, clamping precision and production continuity on the Gildemeister DMG Mori GM16AC multi-spindle lathe. Tadaah offers this component as a functional part of the main spindle group, to be assessed not only for dimensional compatibility but also for its kinematic role in rotation transmission, clamping finger control and controlled closure of the Q0001870 bar clamping collet.