Net Sales for the three months ended March 31, 2022 increased by $7,677,000, or 27.2%, to $35,905,000 as compared to $28,228,000 for the same period a year ago. Sales for the nine months ended March 31, 2022 increased by $21,758,000, or 27.7% to $100,364,000 as compared to $78,606,000 for the same period a year ago. The increase in sales for the three months ended March 31, 2022 was due primarily to increased recurring communication service revenues ($3,139,000) and sales of intrusion and access products ($3,712,000) and door-locking products ($826,000). The increase in sales for the nine months ended March 31, 2022 was due primarily to increased recurring communication service revenues ($8,927,000) and sales of intrusion and access products ($8,714,000) and door-locking products ($4,117,000). The increase in hardware sales are due, in part, to the increase in customer demand after the decline that resulted from the COVID-19 pandemic.
Overall gross profit for the three months ended March 31, 2022 increased to $15,033,000 or 41.9% of sales as compared to $12,910,000 or 45.7% of sales for the same period a year ago. Gross profit on equipment sales for the three months ended March 31, 2022 decreased to $4,539,000 or 19.0% of equipment sales as compared to $5,261,000 or 27.2% of equipment sales for the same period a year ago.
Overall gross profit for the nine months ended March 31, 2022 increased to $39,932,000 or 39.8% of sales as compared to $35,005,000 or 44.5% of sales for the same period a year ago. Gross profit on equipment sales for the nine months ended March 31, 2022 decreased to $11,003,000 or 16.4% of equipment sales as compared to $14,269,000 or 26.3% of equipment sales for the same period a year ago.
The decrease in gross profit on equipment sales and gross profit as a percentage of equipment sales for the three and nine months was primarily due to continued inflation of freight and component part costs relating to the current, world-wide supply chain problems, an unfavorable shift in product mix to the Company’s Starlink radio products (products which lead to the more profitable recurring service revenues) as well as more aggressive promotional pricing of these radios in order to increase the Company’s market share of these products.
Gross profit on service sales for the three months ended March 31, 2022 increased to $10,494,000 or 87.2% of service sales as compared to $7,649,000 or 86.0% of service sales for the same period a year ago. Gross profit on service sales for the nine months ended March 31, 2022 increased to $28,929,000 or 86.9% of service sales as compared to $20,736,000 or 85.1% of service sales for the same period a year ago. The increase in gross profit on service sales was due primarily to the 35.3% and 36.7% increases in sales of these services for the three and nine months ended March 31, 2022, respectively, as compared to the same periods a year ago as well as the continued shift in mix to the company’s fire radio services, which typically have a higher margin than those for intrusion radio services.
Research and development expenses for the three months ended March 31, 2022 increased $107,000 to $2,009,000, or 5.6% of net sales, as compared to $1,902,000, or 6.7% of net sales, for the same period a year ago. Research and development expenses for the nine months ended March 31, 2022 increased $243,000 to $5,918,000, or 5.9% of net sales, as compared to $5,675,000, or 7.2% of net sales, for the same period a year ago. The increase was due primarily to increased payroll while the decrease as a percentage of net sales was due primarily to the increase in net sales.
Selling, general and administrative expenses for the three months ended March 31, 2022 increased 41.2% to $8,442,000 from $5,980,000 for the same period a year ago. Selling, general and administrative expenses as a percentage of net sales increased to 23.5% for the three months ended March 31, 2022 as compared to 21.2% for the same period a year ago. Selling, general and administrative expenses for the nine months ended March 31, 2022 increased 33.4% to $23,983,000 from $17,979,000 for the same period a year ago. Selling, general and administrative expenses as a percentage of net sales increased to 23.9% for the nine months ended March 31, 2022 as compared to 22.9% for the same period a year ago. The increase in selling, general and administrative expenses was due primarily to increased sales incentive compensation relating to the increase in net sales as discussed above, as well as an increase in tradeshow and non-recurring legal expenses.
Other income (expense) for the three months ended March 31, 2022 decreased $133,000 to expense of $177,000 as compared to expense of $44,000 for the same period a year ago. Other income (expense) for the nine months ended March 31, 2022 increased $3,855,000 to income of $3,802,000 as compared to expense of $53,000 for the same period a year ago. The change in Other income (expense) was due primarily to the gain from the extinguishment of the Company’s $3,904,000 in PPP loans, which were forgiven by the SBA during the first quarter of fiscal 2022.