Although the loading of glass beads is predicted to be ~4.8 times lower than glass wool, the quantity of oligos produced on them under typical small scale synthesis conditions is still predicted to be higher than 1 pmol, the quantity sufficient for most biological applications. For example, with 100 mg glass beads with a loading of 256 nmol/g, assuming an average stepwise yield of 99.7%, which corresponds to an overall yield of 0.25% for a 2,000-mer synthesis, the quantity of full-length oligo is ~64 pmol. Considering that glass beads are easier to handle and less likely to generate fine particles that may block the lines of synthesizer, we decided to test long oligo synthesis on glass beads for the purpose of comparison with glass wool. The glass beads (Figure ) were functionalized using the same procedure for functionalizing glass wool (Scheme 2). The loading was determined to be 256 nmol/g (Entry 6, Table ), which is close to the calculated value 249 nmol/g (Entry 4).