Why don't you contact BWE Ltd directly using the information below or by writing them directly from their web site. That way you will get a good technical answer. Then, please share the information with all of us here. Thanks.
Beaver Business Park
Tel: +44 (0) 1233 627 736
Fax: +44 (0) 1233 630 670
Web Site: www.bwe.co.uk/
Peter J. Stewart-Hay
Stewart-Hay Associates www.Stewart-Hay.com
519 641- 3212
Note - A day or so later, I did contact and invite BWE to respond to this query on the web site. They did not bother.