<p>ME-1 is a stainless steel screw shaft and and ME-2 is a nut made from a tribological resin. This part combination can be used without grease. I ordered the part combination from <ahref = 'https://us.misumi-ec.com/vona2/detail/110302642530/?PNSearch=MSSRW401-150-F6-V2.5-S6-Q2.5&HissuCode=MSSRW401-150-F6-V2.5-S6-Q2.5&searchFlow=suggest2products&Keyword=MSSRW401-150-F6-V2.5-S6-Q2.5'> here</a>, where I configured the product by looking at the table under the tab "Drawing/Specificaitons". Initially, I snap fitted one linear bushing (ME-5) in each of the slider wings sitting on the left side (3DP-1 Part) and the right side (3DP-2 Part) of the main slider (3DP-2). Then, I fitted one linear bushing in each side of teh main slider. I sourced these bushings from <ahref = 'https://www.amazon.com/uxcell-Double-Rubber-Bearing-Bushing/dp/B0742RT5FV/ref=sr_1_2?s=industrial&ie=UTF8&qid=1520998572&sr=1-2&keywords=LM4UU+Linear+Motion+4mm+Ball+Bushing&dpID=41MaFqlG%252BZL&preST=_SY300_QL70_&dpSrc=srch'> Amazon</a> in a really good price!!! After screwing the lead in the nut, then I snap fitted the sub-assembly in the slider (3DP-2 Part) and tight fitted the two parts with screws (ME-4 Part).</p>