Sub-Attributes

The default variations will do this.

Just set up two attributes – for example:

Type: Vial | Syringe
Size: 0.1 | 0.2 | 0.3 | 1 | 4 | 6

If you add these to the product Attributes tab then in Variations add each Type/Size option.

When you go to the propduct page and select Vial – only the Vial options will appear.

Have a look here:

https://clothing.b46it.com/product/classic-hoody-logo-embroidery/

Pick size L and all the colours are available.
Pick size 5XL and only a few appear

Got it. Thanks so much!

@48fourteen here is our documentation that covers what @seank123 suggested – https://docs.woocommerce.com/document/variable-product/#manually-adding-a-variation

We haven’t heard back from you in a while, so I’m going to mark this as resolved – if you have any further questions, you can start a new thread.