This is a slug strainer for aquarium. Water syphon strainer. It wil be useful whille you cleaning aquarium water, small fish or big object will be restricted by the strainer. Approximate size of the holes are 3mm. Use in the aquarium where the fisher are bigger than 3mm. So small fish will not suck by water dranage pipe. Specially while water syphoning.
Custom size and design possible. Please contact with me for more details.
Thanks,Mahbub