becket load 150 not to compress sides and balls 68 a and 68 b side must be extended upwards and a compression piece 142 employed in order for block to operate efficiently if the block is constructed as in left hand side of fig6 b with becket loop 154 attaching to bobbin 152 which bobbin has sufficient width so that compression loads from becket 154 do not pinch sides but are absorbed by central portion of block at 156 a and 156 b then a lighter more advanced becket block is provided it should be noted that becket loop 154 may pass through center of block or bypass block at 154 fig7 shows a section of a ball bearing row 120 with balls 122 and non bearing element lubricating spacer 124 between selected balls the lubricating element shown at 126 is made of a plastic such as teflon which rubs against balls 122 during use leaving a coating of lubricating plastic on balls 122 and race 120 element 126 is shaped to fit in race 120 and has opposing concavities 128 a and 128 b to provide the maximum of contact area and the minimum of space between balls 122 such that bearing loads are not significantly increased fig7 a shows a cross section of a roller bearing row 130 with balls 132 and cross section of lubricating element 134 between selected rollers the element shown at 136 is made of a plastic such as teflon which rubs against rollers 132 during use leaving a coating of lubricating plastic on rollers 132 and race 130.