Reaming shell is set with natural or synthetic diamond, and it is used to couple the drill bit with the core barrel. Its main function is to ream the hole to the correct constant specific diameter which ensures adequate clearance for the core barrel and sufficient clearance for the new bit which replaces an old one. It also acts as a stabilizer for drill bit.
Size Available:

"Q" Series: AQ,BQ,NQ,HQ,PQ(Front end  & Back end Type)
T Series: T36,T46,T56,T66,T76,T86
WF Series: HWF,PWF,SWF,UWF,ZWF
WT Series: RWT,EWT,AWT,BWT,NWT,HWT(Single Tube/Double Tube)
WG Series: EWG,AWG,BWG,NWG,HWG(Single Tube/Double Tube)
WM Series: EWM,AWM,BWM,NWM
T2/T6 Series: T256,T266,T276,T286,T2101/T676,T686,T6101,T6116,
              T6131,T6146,T6H
Others: NMLC,HMLC,LTK48,LTK60,TBW,TNW,ATW,BTW,NTW,AQTK
        NXD3,NXC,T6H,SK6L146,TT46,TB56,TS116,CHD101

All Chinese Sizes.