Brass compression fittings. BS 864-2:1983 or BS EN 1254:1988. They conform to both these standards apart from marking: a fitting conforms to the standards with which it is marked.
https://www.bes.co.uk/35-mm-x-28-mm-reducing-set-17741/39735Compression Reducing Set - 35mm x 28mmhttps://www.bes.co.uk/media/catalog/product/3/5/35-mm-x-28-mm-reducing-set-imported_min_17741_P_1.jpg2.072.07GBPInStock/Pipe Tube & Fittings/Pipe Fittings/Compression41671241424145<p>35 mm x 28 mm reducing set.</p><p>Brass compression fittings. BS 864-2:1983 or BS EN 1254:1988. They conform to both these standards apart from marking: a fitting conforms to the standards with which it is marked.</p>BESt range00https://www.bes.co.uk/media/catalog/product/3/5/35-mm-x-28-mm-reducing-set_min_17741_L_1.jpghttps://www.bes.co.uk/media/catalog/product/3/5/35-mm-x-28-mm-reducing-set-imported_min_17741_P_2.jpg5056198111436add-to-cartfacet_type:Reducing Setspecial_price:2.070000cat_multi_facet_l1:Fittingsmore_sizes:17734,17735,17736,17737,17738,17739,17740,17742,17743products_related:7623,9570,8199,16444,23208,7308,7389,7550,21112,19494,23366sku:17741FittingsReducing Set17734,17735,17736,17737,17738,17739,17740,17742,177437623,9570,8199,16444,23208,7308,7389,7550,21112,19494,23366177412.070000No{"Type":"Reducing Set"}ReducingBESt rangeBrassMetric35 x 28 mm