Bugaboo Locking Disk Left Side (Brake Lever Side) This model is solid for maximum strength when used with plastics. It costs $50 in stainless steel so I had a hollowed out version made for the stainless steel option. I find a lot of Bugaboo's with hollowed plastic disks so I will now offer that option as well. Check out my hollowed out file for a $10 WSF of $12 BSF option