The new Perth Mint bar mark as registered with the LBMA. Smaller bars will have the same swan mark but words around it in a circle. The bar pictured is a 400oz bar, 9960 being the purity (99.6%) and the year and bar number (see Good Delivery rules). Weight is specified on a bar listing as per LBMA rules page 9:
"It is strongly recommended that weights should not be stamped on Good Delivery bars. The reason for this is that when bars are weighed in London by an LBMA approved weigher their weights, which may be different, will prevail, and also any adjustment to the weight of a bar caused by future handling or sampling would necessitate alteration to the mark. If bars are so stamped, the unit of weight must be shown."
Below is picture of a bar stack for you to drool over.