❶Q-A-Question:Question：9 1/2 size up or down?Answer: It is recommended that you purchase size 10, if it is not suitable, you can contact us to replace it for you. ❷Q-A-Question:Question：Could these be worn in the poop for water aerobics?Answer: Well, I don’t intentionally wear anything in poop so I am not sure I can help you out on that. However, if you’re asking about wearing them in a pool I would say probably not. They don’t seem like they are tight enough to stay put in water. However they are super comfortable shoes and super cute to wear! ★★★★★ NOTE: Please compare the detail sizes with yours before you buy!!! Use similar shoes to compare with the size.Size Chart:Size: 35 EU: 35 UK: 3.5 US: 5.5 CN: 225 Foot Length: 22.5cm/8.9" Foot wide: 8-8.5cm/3.2-3.4" Size: 36 EU: 35.5 UK: 4 US: 6 CN: 230 Foot Length: 23cm/9.1" Foot wide: 8.5cm/3.4" Size: 37 EU: 36 UK: 4.5 US: 6.5-7 CN: 235 Foot Length: 23.5cm/9.3" Foot wide: 8.5-9cm/3.4-3.5" Size: 38 EU: 37 UK: 5 US: 7.5 CN: 240 Foot Length: 24cm/9.5" Foot wide: 9cm/3.5" Size: 39 EU: 38 UK: 5.5 US: 8 CN: 245 Foot Length: 24.5cm/9.7" Foot wide: 9-9.5cm/3.5-3.7" Size: 40 EU: 39 UK: 6 US: 8.5 CN: 250 Foot Length: 25cm/9.8" Foot wide: 9.5cm/3.7" Size: 41 EU: 39.5 UK: 6.5 US: 9 CN: 255 Foot Length: 25.5cm/10" Foot wide: 9.5-10cm/3.7-3.9" Size: 42 EU: 40 UK: 7 US: 9.5-10 CN: 260 Foot Length: 26cm/10.2" Foot wide: 10cm/3.9" Size: 43 EU: 41 UK: 7.5 US: 10.5 CN: 265 Foot Length: 26.5cm/10.4" Foot wide: 10.5cm/4.1"