It seems very odd to me that although the price of the Promega protein G magnetic beads is the same as the competitors their capacity is a least 40 times higher. Have you used it and can help me out?
Promega beads (18 mg IgG/1 ml of beads) : http://worldwide.promega.com/products/protein-purification-and-interactions/magnetic-systems-for-purification-of-antibodies-and-affinity-tagged-proteins/magne-protein-g-and-magne-protein-a-beads/?utm_source=url_magne&__utma=1.1430002545.1390905203.1390905203.1390905203.1&__utmb=1.1.10.1390905203&__utmc=1&__utmx=-&__utmz=1.1390905203.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)&__utmv=-&__utmk=69726480
Pierce beads (0.6mg IgG/1 ml of beads): http://www.piercenet.com/product/protein-g-magnetic-beads
NEB beads (0.4 mg IgG/1 ml of beads): https://www.neb.com/products/s1430-protein-g-magnetic-beads
Life beads (0.24 mg IgG/1 ml of beads): http://tools.lifetechnologies.com/content/sfs/manuals/DynabeadsProteinG_man.pdf