Chastity and orgasm denial discussion

Hello all, I realize this topic has come up before and might be the most pressing question in chastity, but. I’m still unsure about which device to buy. When flaccid my measurements are: 4.5cm wide 10cm long After looking around, nothing seems quite right for me. The curve (which I believe is the main factor?) appears too narrow? Or should it fit tightly like that? Any guidance would be wonderful. Thanks beforehand, Obedientboy