The Ansmann CR2032 3 V lithium battery is a button sized cell suitable for many varieties of calculator, watch, etc.
Price: £2.49 from Wex Photographic
The Ansmann 4LR44 is a 6V alkaline battery for use with various electronic devices.
The Ansmann Battery Box can hold up to 8 of any one of AA, AAA, or CR123A batteries or a number of memory cards.