In the UK, 0844 numbers are classified as Special Rate.. From a BT landline, 0844 calls will be charged up to 6.2p per minute, varying by time of day.
As your fastener distributor will confirm, an external tooth lock washer works well with larger headed screws, including round or pan head. Internal tooth lock washers, on the other hand, are best combined with screws presenting smaller heads, including fillister head fasteners.
A fender washer is a flat washer with a particularly large outer diameter in proportion to its central hole. They are commonly used to spread the load on thin sheet metal, and are named after their use on automobile fenders.