How can I remove the black border from Select component of Native Base?

Question

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I'm using from native base to select the values of locale and timezone field. But there's this black border which surrounds the Select element. So how Can I remove that border ? I tried setting borderWidth to 0px as well as changing borderColor attribute but nothing seems to be working. The Select element is inside Controller of FormControl.

Code for locale select

<Controller
                            control={control}
                            render={({ field: { onChange, value } }) => (
                                <Select
                                    accessibilityLabel={t('screens:regionSettings.placeholders.selectLocale')}
                                    placeholder={t('screens:regionSettings.placeholders.selectLocale')}
                                    selectedValue={value}
                                    variant={'unstyled'}
                                    borderColor={'secondaryLight.100'}
                                    onValueChange={(val: string) => {
                                        onChange(val);
                                        setLocale(val);
                                    }}
                                    {...selectProps}>
                                    {renderOptions(allLocales)}
                                </Select>
                            )}
                            rules={{
                                required: t('screens:regionSettings.errors.enterLocale') as string,
                            }}
                            name="locale"
                        />