Ultra Mini Joist Hanger 50mm. THE ULTRA MINI JOIST HANGER. Our Mini Joist Hangers Work With Both 3.75mm Twist Nails & 3.5mm Screws. Joist Support System. Thats Why We Made Our Hanger Small Enough That It Works With These Type Of Jobs But Strong Enough So It Works With Them Bigger & Heavier Jobs.