Normally you will need two chops minimum. One is the full company name + reg. no. + full address. You may also want to fit in the tel, fax and even contact person/email/etc.

The other is a smaller chop, normally round. With just the company name + reg. no. only. This is used for signing receipts, letters/couriers, etc. where only small space is available to chop.

Some will have a third chop with just company name + reg no. in a straight line. To chop cheque book if too lazy to write or cannot afford a cheque franking machine.