wall 211 of at least about 2 inches more preferably about 3 inches to about 9 inches in some embodiments the first tube 210 is generally cylindrical with the inner and outer diameters 254 and 255 of the cylinder gradually increasing from the top 214 to the bottom 216 e g a slight taper to facilitate injection of the first tube 210 during plastic injection molding the first tube wall 211 may have any desired thickness 258 depending on the strength desired and the cost of the material in some embodiments the first tube wall thickness 258 is from about 0 05 inches to about 2 inches optionally the first tube 210 includes a knurled surface 252 at the top 214 of the first tube 210 for gripping preferably the bottom 290 of the first tube slot 221 is adjacent to more preferably about co planar with the top 231 of the first flange 230 as shown in fig4 5 8 9 10 13 16 18 24 26 29 31 and 34 preferably the first tube slot 221 extends from the first flange 230 to the top 214 of the first tube 210 preferably the first tube 210 is immobile relative to the first flange 230 in some embodiments the first flange 230 is configured so that it alone or in combination with.