Since I have one I thought it would be easy to look up in the owner's manual, but it only describes them as "fixing bolts" without giving the size of the bolts. Their long with an allen wrench head, without dismantling mine, I want to say maybe 1/4 inch thread and they require a washer too. Sorry I can't be of more help, but I would just try a few sizes and see.
I've got the bolts out on mine (not an xl, but should be the same). I'll send you the measurements when I get home if you don't have an answer already.
Ok. Now I'm not an expert on this stuff, so take this with a grain of salt. I'm pretty sure that it's a 55mm long hex head cap screw (Class 8.8 DIN933) with an M8 body diameter (8mm measured outside thread diameter) and a thread pitch of 0.8 threads per mm. Hope this is right and helps.
I emailed KHB Photographix and made an inquiry about those bolts and they sent this back to me----could of posted this a few days ago but kinda forgot.
CP
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"Thank you for your inquiry. The baseboard bolts are part #OS32084516, and we have them in stock at $1.50CDN each. Shipping for small parts and accessories is a flat rate $12.00 within Canada or $16.00 to the USA. You might want to consider if there is anything else you might need to purchase that could ship with the bolts for the same flat-rate shipping fee.If you would like to place an order with VISA or MasterCard, you can use our secure on-line order page athttps://secure9.securewebexchange.com/khbphotografix.com/order.htm
Please contact us at your convenience if we can be of further assistance.Kindest regards,Dave Etherington
If you have any of the bolts then take one to the hardware and have it matched. If you dont have any bolts, take the baseboard to the hardware and find ones that fit. Make sure they are not so long as to protrude through the bottom and hit the counter top.