有一个客户,说的想要的尺寸,在我们的行业产品里根本没有这个尺寸.我怎么问比较好呢?

you did not even know what size or specification of products you want,therefore we cannot provide you with the samples.（这样说比较不客气）
所以你可以说出：
i will provide you with the samples if you can offer the correct specification.what you offered us before does not even exist,please check on that.