This adapter is designed to hold the following:
15 mL Conical Tube

These adapters will hold 9 tubes. In other words, each adapter has 9 slots.
Your purchase includes four (4) adapters.
This means you will be able to spin a total of 36 tubes with this purchase.This Adapter Works with the Following

4 x 400 mL Round Buckets

Accessories for Set of 4 adapters 9 x 15 ml conical