The Canon OC-E3 Off Camera Shoe Cord maintains all on-camera flash functions including E-TTL / E-TTL II for one Canon Speedlite used off-camera at distances up to 2'. It is compatible with all Canon EOS cameras except the EOS 630 and EOS RT which require a combination of TTL Hot Shoe Adapter 3, OA-2 Off Camera Shoe Adapter, and Connecting Cord 60.
The OC-E3 has been improved over the OC-SC 2 with better sealing against dust and moisture, to better match the weather-resistant design of the EOS 1D Mark III and the 580EX2 flash. It also now features a sturdier foot.
Also fully functional with the combination of the T90 camera and 300TL flash (from Canon's older FD manual focus system).