Dibutyltin Dilaurate
DBTDL - C32H64O4Sn
25% solution in alcohol with blue dye added - makes measuring a lot easier!
For use as a cure catalyst
Skin Irritant - Do Not Take Internally - Keep out of reach of Children!!

Generally, about 0.1% DBDTL is used in an HTPB mixture so you would have to add 0.4% of this solution to get the same ratio.  One bottle will last the average experimental motor maker a long time as a couple of drops will speed the reaction significantly.

See Safety Data Here

8 ml bottles, $4.00 ea.