The concave bottom mill shoe is used to grind downhole small objects and other unstable fallen objects.

Technical specifications and parameters
 

 

Type	OD (mm)	Connection(Box)	Hole size(mm)
MA89	89	2 3/8 REG	95.2-101.6
MA97	97	NC26	107.9-114.3
MA110	110	NC26	117.5-127.0
MA121	121	NC31	130.0-139.7
MA130	130	NC38	142.9-152.4
MA140	140	NC38	155.6-165.1
MA156	156	NC38	168.0-187.3
MA178	178	NC50	190.5-209.5
MA200	200	NC50	212.7-241.3
MA232	232	NC50	244.5-269.5
MA257	257	6 5/8 REG	273.1-295.3
MA279	279	6 5/8 REG	298.5-317.5
MA295	295	6 5/8 REG	320.6-346.1
MA330	330	6 5/8 REG	349.3-406.4
MA381	381	7 5/8 REG	406.4-444.5