The grease fitting is used in a bearing.
uxcell Steel Straight Grease Fitting M8 x 1mm Thread x 1mm, Silver Tone
uxcell 304 Stainless Steel Straight Grease Fitting M10 x x 1mm, Silver
uxcell 304 Stainless Steel Straight Grease Fitting M6 x 1mm Thread x
uxcell 304 Stainless Steel Straight Grease Fitting M10 x 1mm Thread x
uxcell Brass Straight Grease Fitting Assortment M8 x 1mm Thread Hydraulic Grease
uxcell Brass Straight Grease Fitting M5 x 0.8mm Thread x 0.8mm, Yellow