Shimano ST-5700 10sp STI Bracket Cover (Hoods) From  £9.99

After several cable changes my right rubber cover was like a sock with no elastic and was moving and sagging.. Bought these genuine replacement... Easy to fit with a bit of effort just yark them off and new ones on... Checked you tube and the advice was use alcohol hand sanitizer that will evaporate as lube to help them on... You can really stretch then they take a lot of abuse