Oil return fitting size Sr20det

[s14sliding]

Here's a pic of my oil return fitting I took off my sr20det I can't figure out the fitting size so that I can replace with a 10an fitting. Anyone know the fitting size that fits so I can finally finish this build. Thanks. 6104661047

[240knockout]

-10 AN to 1/2 BSP Adapter Fittings with Dowty Seal (http://www.z1motorsports.com/upi/product_info.php?products_id=4950)