Google has summarised the Shopping Products feed specifications for 2016 and has indicated time-lines for implementation. These include:-
Unit Pricing for all markets will be required by September 1st.
'Color' and 'size' attributes for apparel products in Germany, France, Japan, and the UK are to be enforced more strictly from September 1st.
‘Gtin’ and ‘google product category’ requirements are being extended to Austria, Belgium, Canada, Denmark, India, Mexico, Norway, Poland, Russia, Sweden, and Turkey and will be in full effect starting February 14th, 2017.
The minimum image size requirements for non-apparel products is to be increased from 32 x 32 to 100 x 100 pixels to better support new ad formats. Additionally, apparel ads sizes will remain at 250 x 250 pixels. High quality images should be 800 x 800 pixels or more. Images smaller than the requirements will mean disapproval of the ads from September 1st.
Google is increasing the maximum feed file size from 1 GB to 4 GB from September 1st.